You can have a "warning" before a technical foul -- see all the "delay of game" rulings.

THe OP only said it was a warning. S/he didn't indicate what the MI ruling was if the team didn't stop.

Hey, who's the new guy making me look bad?

Yeah, Stosh, I know it's not a perfect interpretation. But I think that's it's just as valid to say it's unsporting as it is to say that it's nothing, since the NFHS hasn't ever said anything about it.

The warning could be considered a courtesy, like warning a coach to get back in the box, before a T is issued.