A blessing on your head, Mazel Tov, Mazel Tov

This scenario happens a lot:

Me: *coughitycough*

Them: Bless you!

Me: Thanks.

Them: Wait--did you sneeze or cough?

Me: That was a cough.

Them: Oh. Never mind, then.

What the heck?

They'll bless me if I sneeze but a cough somehow doesn't rank a blessing?

Am I any less in need of a blessing if I cough than if I sneeze?

Now I'm not generally one to turn down a blessing from anybody but based on their "only sneeze" policy, when I do sneeze and they bless me, how much stock should I put into it?