truerookie wroteWhat the big deal? I've seen a state high school (playoff championship) game where every girl on the team wore the shirt you described. Without corrections
At the moment the legality of a long-sleeve undershirt in NFHS play is unclear.
I spoke to the rep on the rules committee from my state about it last week during our state tournament.
However, there is no such ambiguity at the NCAA level. The rule is very specific.