Pregame Dunk

[Chess Ref]

I was the R for a mid-level Boys Varsity game last night. As I'm at the table going over the book there's some slight crowd noise behind me so I turn around and there's nothing going on. Partner is in position and watching players. I go back to finish up with table and the crowd makes some more noise, once again I turn around and there's nothing. Partner is watching players and in position.
So before tipoff I ask partner about the noise. A player from both teams had a minor dunk off apparently. I asked partner how we were gonna handle the T's. Partner then went into the whole spiel about not starting the game off that way, blah,blah, blah. We discussed it and he basically wasn't going to give the T's. We left it at that.

My questions are could I have penalized the dunks even though I didn't see them ?

Have you guys and gals ever enforced this rule ? Or would this fall into the OOO realm of things ?

PS. As a side note partner had big concerns about kid hanging on the rim on a alley oop slam dunk with about 5 players under the rim,bodies falling, type of play..

PPS Its cool that I'm starting to get games like this ,where kids alley oop and stuff like that....