How are things between you in real life? How does she behave with you when you are together? This might be a better gauge of her intentions than her facebook comments.

The thing about facebook/online communication is that intonation and expression isn't there - and some people have a certain style - I have some facebook friends who sign off every comment with a kiss for example. Not saying she isn't keen on you but just that her face to face behaviour would be more accurate.