Well it's a problem anyway... i didhad that same problem one time with another mod before the first release of GW 1.0, and it's realy anoying i know!!!
But just for the record , it doesn't hapend with all the targets you attack
just some times it comes some of the hard sinking ones...
But yea it's the NYGM damage model this, since GW doesn't had one of is own yet...
this is to change on the next release...