Girls, female friend opinion? continued?

I have a female friend at work. We've worked together for 2 years now. We're really close and she trusts me quite a bit. As a background she has told me that in general she is a shy person. We usually have boundaries up since we're "friends" and both in committed long term relationships but I've noticed that she's touched me on the arm when i make her laugh or I got slapped recently (in front of others) for teasing her about her height. But at other times she seems distant so I can't figure it out. She has called me a really good guy friend before, but then the other day when I returned from vacation she sent an email saying the "office" missed me (i don't have any other friends in the office). We talked today for about 45 minutes after work. I noticed that she crossed and uncrossed her legs, played with her jewelry (but this could be a sign of boredom also). But even though she seemed really comfortable I noticed she had her arms partially crossed (maybe anxious?). Although she seemed into the conversation as she was laughing and actually kept up the convo as I walked away. So does anyone think she might have suppressed feelings or is being friendly?