This is definitely a head scratcher. A guy I know had the same type of thing with C4 happen (although of course he didn't stick the guy). It landed basically right on top of a guy laying prone and didn't kill him. This game fails so much at times.

this has happend to me so many times. that's why i hardly play this game

yea i'm sooooo tired of being 2 seconds behind people i saw an enemy take out two of my teammates so i was aiming and waiting for him to turn the corner i couldn't even shoot before he already killed me i had no chance ... i'm couple seconds behind everybody and it's really frustating

If he had some sort of armor of blatshield an emblem would appear over the hit marker. But I've seen people stand on top of claymore, stand under a Pred Missile and such. Sadly this doesn't surprise me