My dog whimpers when ever my husband touches him.?

He's about 6 months, and is a blue-healer/samoa mix.. When we first got him my husband played roughly with him and he LOVED it.. When we started training him my husband and I decided the best coarse of action was to treat him as if he was one of the pack. If he did something wrong we'd place him on his side and hold him to the ground, not in a way to hurt him, just to show him that we are Alpha.. If he did something REALLY bad he would get a spanking, either lightly on his butt or on the top of his head. We know we aren't hurting him while disciplining him, but a few weeks ago he started to yelp if my husband put a hand on him. At first I thought my husband was hurting him in some way and I'd yell at him to leave the dog alone which he would do automatically. The only problem with this was I realized that the dog stated doing it even while they were playing, and I know that doesn't hurt him because I play the same way with him. I think that he is yelping at my husband when he's being disciplined because he knows that I'll panic and yell at my husband to stop and that he will get out of being in trouble. When I discipline him in the same way he doesn't cry. I know it's not a strength problem because I actually happen to be stronger then my husband.. Am I right in my assumption, does he yelp just to get out of trouble?