TNT above TNT will not be primed when the TNT at the bottom is ignited first.

When i put TNT on a TNT and prime the bottom TNT first, I fly up and tap the TNT above it. The TNT got tapped(by turning a bit lighter and returning to normal when un-tapped) but did not detonate. Why is this?
Also something similar. I can tap minecarts through solid blocks. Very annoying (and a bit useful sometimes). FIX the TNT bug by 0.8.2/0.9.0!