^^^ This,this,this!
My friends applying for school this year are all in different subfields than me, so I know I didn't exactly "steal their spot" in any lab... But I feel guilty getting into a PhD program when one of my friends didn't, and he has a lot of research experience and has known what he wanted for a lot longer than I have. I know I got in with a lot of dumb luck... But I still feel bad. >_<
Also, don't bother saying "Don't feel bad!", because the feeling doesn't go away with reason. Heh.