Play in a Scrimmage Game

[stripes1977]

Just want to see how some of you might have handled this:

I am working as head linesman on the short side of the field. The play goes up the middle, a run. A receiver is blocking a defensive player away from the play and the defensive player's jersey becomes untucked. He starts to backpedal to get away and the receiver (in my mind) basically had his hands caught in the jersey. By now the jersey is nearly over the head of the defensive player, who finally falls down. He's obviously embarassed b/c he was driven out of the play with ease and now his shirt is over his head. He gets up and smacks the receiver in the helmet. Of course I flag it, push them apart, and the defensive player is ejected (thank God it was the last play of the scrimmage).

What made this play wierd was the untucked shirt and the fact that the receiver just kept on blocking the opponent (as I think he should) with his hands in the jersey. Is there anything that the receiver did that would be illegal?? He didn't purposely pull the guy's jersey up, but once that happened, would he be allowed to block with his hands "tangled" in the jersey? Basically I was able to see the whole act, and I am trying to see if there was anything the receiver did that I should have flagged, or if the defensive player was just a hothead.