I had an experience similar to your's just last night! A friend brought her 45 lb., 4 month old lab over to play with Myles last night (Myles is about 80 lbs.). They've played before but Duke (lab) was a lot smaller then so we thought they'd be better playmates now. They played just fine with Myles using his paws to play and hold Duke down. Well, Duke didn't care to be taken by Myles and started biting Myles in the face and neck. Myles was being really good with Duke and not biting back or growling or anything (but he's also been trained not to bite, unlike Duke). I didn't realize how serious it was until they'd left and I saw that Myles' neck and a couple of spots on his chest were really red and upon closer inspection, there were teeth marks! I was really upset! I took his collar off so it wouldn't rub against his skin and I washed it a little with a washcloth. Was there something else I should have done or that I should do now? He doesn't seem to be real bothered by it so maybe I shouldn't either. I feel so bad for my baby! :( And I plan to tell my friend that I won't let her bring her dog over until he's gone to puppy class and stops biting!