it was sort of unexpected for me. i've known this guy for about year and a half now (we work together) but we've had relatively very little interaction. but for the past week and a half, we've been working together kind of closely. i'm not sure now it happened, but i feel like we've gotten a little playful with each other. from what i know of him, he's a very intelligent, nice, but also very introverted guy. he's not shy, but more reserved. other people have described him as "odd" and doesn't tend to make too much eye contact with people.
when we are at work, we don't get too much "alone" time, but we do tend to playfully tease each other (and it is generally work related stuff). i dont' think anyone else notices. and maybe it's all in my head anyway. he's always been a facebook friend of mine and lately we've been posting funny comments on each other's walls and writing messages. it's all playful work related stuff tho. now i find myself thinking about him and smiling a lot. he seems like someone i genuinely enjoy spending time with and would love to get to know him. i just dont' know how to transition from coworker to possible friendship/romance. i know this is stupid, but although i do sorta feel a vibe from him, how can i tell if he's interested?