The Case of the Missing Tea bag...

Avid readers of "on the road with Pierre and Murphy" may remember several incidents involving food vanishing from the fridge from the kitchen in my old student housing. And how I could tolerate many things - except people taking my cucumbers. And stealing my milk. Back then, there were 28 suspects - the 27 people you lived with and had a key to the kitchen and yourself (the famous - I couldn't have eaten the whole bar of chocolate-phenomena).
Now I live with 5 other people. That definitely limits the pool of suspects should anything vanish from the fridge - actually at least one of them has her own fridge having moved from one of the undergrad dorms that don't have a kitchen. I don't mind if somebody "steals" a sip of my milk for their coffee/tea (by the way, between the five of us we cover every kind of milk from colored what no fat - no milk - no taste as I like to call it, to "real" milk).
I do mind if somebody declares my milk "empty" and throws it out late nigh/early in the morning even though I purposely left juuuust enough milk in there for my breakfast tea. But that's beside the point.

I have had a nagging feeling that somebody, SOMEBODY, somebody you see has secretly been using my sugar. I realize this could fall under the "I can't believe I ate all that chocolate"-phenomena, but the longer this has been going on, the more sure I am getting about it. And nobody else has a sugar pot (or a sugar bag) and everyone drinks tea and/or coffee. I suppose I can live with this... even though at some point the sugar thief should feel bad about it and refill my pot.
I also mind when somebody steals my cocoa. I know this onefor a fact. Because I bought cocoa to bake and then didn't use it for a week and when I went to bake something chocolatey for the firfirst time, somebody had already opened it. Thought it's quite confusing how that person knew it was there... they would have had to work their way through the entire cupboard as it was in the back right corner.
I ran into one of my suit-mates when I came home from practice ones to find her violently stiring her pasta. I made a typical "Shannon-comment" not realizing she was actually violently sitrring - turns out she was a bit upset, because somebody had used up her jar of tomato sauce. I understand, that one might accidently use the wrong jar. I'm the only one who spices her own sauce, everyone else uses the pre-made kind.
Yes, I am getting to the missing tea bag. So there is something weird going on and probably at some point I'll get annoyed enough to figure out what is going on and confront my room mates. But here is what just happened - and I really, really cannot come up with a good way of explaining this one.
I went to the kitchen area to make a cup of tea and prepare a bowl of cereal (preparing a bowl of cereal is an art to itself). According to my usual procedure, while I boiled water I prepared my cereal (except the milk, I don't like soggy cereal), added milk, sugar and a tea bag to my mug and when the water had come to a rolling boil I poured it into my mug. Then, I went to my room to quickly check my email while my tea was steeping.
I got distracted for about 5 minutes and then said to myself: Shannon, you should probably go add milk to your cereal and pull that tea bag out of you mug.
So I went back to the kitchen.
And there no longer was a tea bag in my mug.
I'm serious.
And I KNOW I didn't take it out earlier. I am POSITIVELY SURE about this. I can tell
a) by the color of my tea - it wasn't a very strong tea, and I like my tea strong
b) the tea bag was not in the trash or in my tea bag storage place
c) even I wouldn't have taken out my tea bag and then gone to check my email while I waited for it to steep.
So, really?! Seriously?! Steal somebodies tea bag out of their mug?
I would say somebody is trying to mess with me. But I don't know any of my room mates well enough to have offended them/incited them to start stealing my tea bags. I also don't know any of them well enough for them to start pulling pranks. I think I know them well enough to know they're not the kind of people to pull pranks.
And so for once, I have no plausible theory to explain what's going on...
But I'll come up with something.
I'm sure.