I agree. I think you can kind of divide bonding into two parts; the chemicals that cause a 'feeling' and the ability to actively think about that feeling (not in the abstract human sense, but in the "I hope mommy comes home soon!" puppy dog sense). I believe snakes have the first, but not the second.
EDIT: OMG I just scrolled up and saw a typo in my previous post, and it will not let me edit. This bothers me far more than it should.