Hamstring problem post ACL reconstruction?

In January 2009 I had ACL reconstruction surgery using my hamstring tendon. My knee feels awesome, but my hamstring doesn't feel quite right. I still can do all of the exercises I used to be able to do before I tore my ACL. The only problem is that when i feel my hamstring it feels like part of it is missing. It feels really weird and it's starting to worry me because i had surgery 2 1/2 years ago