This will probably sound like a dumb question but here me out. I've been absent from here for a while, and once again missed the beginning of the event(I think I did the same thing last year). I was playing a game and happened to notice that my avatar had a sort of green lipstick mark on her face, but it's not wearing any item that causes this. So the question is, what is it/why is it there?

It's not a kiss mark. I believe it's the first stage of the Baker's Kiss disease. You could find out more about it in the Love Epidemic forums. Hope I helped! (;

Thank you.