Does my boyfriend still like another girl?

am I just being crazy? Or does my boyfriend still like a mutual friend he once had a huge crush on? We have been dating two years and he seems to really love me, but every now and then I get a strange feeling he still has feelings for her. He does not talk about her all the time or always want to hang out, what makes me think this is a few things; we where on a date and she came up in conversation, we where driving and ped her house and he pulled over to call her to see if she wanted to hang out. Another time we where at a party and a friend of ours asked if this mutual friend was single. My bouyfriend replied "no she has a boyfriend." our friend seemed disappointed, my boyfriend the said right in from of me " I know man, I tried too!" and whenever we all hang out he's seems attentive to her, not overtly, I'm probably being sensitive, but I notice, and he likes to walk near her when usually he is near me and holds my hand. I notices he immitates her in certain ways, and always gets all happy when we make plans with her. When we are seated at a table together he is almost always sitting across from her. A few other things happened but that's the general idea. We have all been friends for a several years and he's told me she was a good friend to him, maybe that has something to do with it? I'm not sure what do u think?