Thanks for making me laugh, guys 

I'm probably making too big of a deal out of it... DS seemed to take it in stride.  I guess if kids get red X'ed all the time, it loses its scare value.  And I haven't heard of kids getting teased about it... I think they see it more as a badge of honor.
This may have worked out to his benefit then.  Now, he's really 'one of the guys'.  I'd let it go, I think, at this point.  Yes, I think it was a totally inappropriate punishment.  But if it's an isolated incident, and your son is taking it in stride, I'd count it as a mark of your son's growth for handling it.