hmmmm, I don't know what else to check. I've noticed too that sometimes I don't get e-mail notification. It happens not very often though.
Try replying something, see if effects something .. Double check your profile, check the e-mail address. Maybe edit something in the profile and submit.. this may do nothing though
I really have no clue what the problem it may be. I could speculate, maybe the b-board server is acting out, like being "too bussy". Maybe your e-mail service has/had some temporary issue... and I'd imagine the b-board system sends e-mail once, and if it does not stick at the first attemnt, then this is it, no second chance.