Am I a stalker?? Help?

My best friend at school is a girl.. She is the only good friend i have at school and i am a boy.. So we are friends on facebook and i comment on every post of hers and like everything she posts.. So yesterday, her ex-boyfriend came up to me and told me to stop stalking her.. I never thought i was stalking her until he told me that.. Do you people think i am stalking her?? what should i do to stop it?? I hope she doesn't think i am stalking her.. I consider her to be a really good friend.. and i think she thinks the same about me.. :)