A few Alabama groups began doing this a few years ago (namely Albertville and I believe, Auburn). I believe they bring their own portable sound systems to run those headset mics, which in general makes me feel uncomfortable. The whole headset mic thing makes me feel uncomfortable. But whatev. Not my group.
Honestly, in my time around show choir I've seen it done only a handful of times, but I'm also looking at this from the Midwest. I think it's just one of those things that doesn't happen often enough to have made a rule, or new enough that nothing's been put into place.
From what I've seen, over-ear mics are becoming more popular as bringing an entire PA system for your show is. It makes it easier to run your own sound rather than relying on the house sound guy to do it right every time (no one knows your show better than your own people!). It also makes it easier for soloists with solos throughout the whole show because they aren't having to constantly pick up and put down a microphone.
Just to be clear, nothing was incorrect and nothing needed fixed. Albertville only announced awards for the top 4 choirs in this division which is what was correctly posted. In any case, we're happy to post full placements beyond what was simply announced and have now done so.