Noticed Something i never Noticed since ACM'S Release

I was playing campaign tonight…1st Mission Distress…Right after we cut Keyes down…We walk over to the door with Keyes to get into that room where theres flames/Fire coming from below the floor…B4 we go in that room…theres a Marine stuck on the wall right across from the door…The Marine has a Hole in his chest where the Alien popped out…What I noticed tonight is that there was Blood dripping from the hole in his chest.This is the 1st time I have ever seen Blood dripping from the Hole in his chest.I looked at all the other Marines and theres Blood around the hole in their chest but no blood is dripping…Can some1 tell me why this would all of a sudden happen.I know it never happened B4 and I play this game a lot…I would of noticed it.