Disappearing grenades when you die

[dtk27]

This is driving me nuts!  While playing the game, I will throw a grenade and get killed.  Sometimes the grenade just disappears and sometimes it explodes right on the enemy and nothing happens to him.  I have also found on some maps the grenade just disappears and seems to explode underneath the floor. 

Is this something that can be addressed? I play on the xBox 360 platform.