A harmles bug, but weird to see.

Steps to Reproduce:

1. Gravel
   1. Drop 2 gravel, sand, powder, etc on yourself and look at your hotbar as you sufficate.
2. Horse
   1. Hop on a horse so you can go back and forth under a 2 block tall gap ensuring your head is in a block while on the horse. 
   2. Watch your hotbar while going in and out of suffication.

Observed Resault: Air bubbles show and pop as if you're underwater though you're actually in a wall.

Expected Resault: Air bubbles do not appear while sufficating in a wall.