1 week ago I moved into a new house with 4 other students. The first night we all went out and one of the girls was drunk (as was I) and kept kissing my face. I kissed her face back, and not on the lips as I was not sure what it meant. We went home and sat on the Sofa watching TV before going to sleep. Everything was great, we had a little bonding over common interests.
The second night she called one of our housemates, so we all left to pick her up. On the walk back she kept saying she was cold so we walked home with my arm around her, interlocking fingers. We ended up in her room talking, but other events transpired which interrupted our talk. We went to bed as it was like 5AM.
That was the last time we talked, since then she has not said a single word to me during the day (She was always a bit shy when talking sober but this is different), even when I try and instigate a conversation all I get is one word replies. Often when I enter a room she leaves soon after, or picks up her phone (I'm assuming so I don't talk to her).
What I want to know is what is going on?

If you are both old enough to be drinking... then you are both old enough you can talk to her and ask her what's up. Kids go out of their way to avoid the direct approach wasting weeks or months to avoid a simple question they can have an answer to in 30 seconds or less... adults do the mature thing and are more direct and ask what's wrong knowing they might get an answer they don't want to hear.

Now using some tact is implied when asking her.

Now you can see that alochol use and a spike in stupidity and inappropriate behaviour go hand in hand....for both genders.

I asked her if everything was OK and she said "Yeah". The reason I want outside opinions on the subject is if everything is in my head it will make for an awkward conversation and even more awkward year living in the house with her.

Opinions really mean little from people that don't know her. Different people behave differently in the same sittuations. (you could have ten people and every one of them will react differently than the others) And I've know many, many people in my life to base that observation on.

If you get an awakward answer to a simple direct question, without a lot of people around hearing it... then you can be assured you are stepping into an awkward situation before you find yourself waist deep in it. That's where the Tact comes in... its a sensitive topic... and its best asked without others around listening. You don't even have to be a shy person to be hesitant to say certain things in the presence of others depending on the situation.

She regrets her drunken actions and now she is sober, so she isn't really wanting you to think that a drunken encounter means a chance at romance or even interest.

Only a fool believes a drunk, or thinks drunken behavior is a sign of anything but being drunk. You will find out one day that drunks will do most anything and barely remember it later, or will regret what they do remember. Just wait until you wake up someday and find out that gorgeous creature you picked up last night was a dog with no teeth and a moustache.

Then you will understand what she has gone through with you because she was drunk.

She was drunk and now is embarrassed by her behavior. Just leave her alone. Neither of you know the other at all. Leave it be.