Fall Damage with sprint jumping

Occured in 1.4.2 on a new map in single-player.

While doing the sprinting jump thing to travel long distances faster, I noticed I'm taking fall damage from drops of only 3 or 4 blocks. I'm not sure if it's lag, or if it's a new bug in the update. Either way, it's making traveling in my new 1.4.2 map very annoying.