Clapping for Ourselves

Is it just my own misperception (which spellchecker doesn't like but dictionary.com says is okay), or did clapping become reinvented or redefined sometime within the last few decades. I noticed it again a short while ago watching So You Think you Can Dance Canada. When they acknowledged the choreographers, and the audience clapped for them, but the choreographers clapped too.

I wonder when the fashion changed, or maybe it didn't where you're from? Maybe it was always that way in some circles? But in my memory, when people clapped for you, you accepted it quietly and humbly. You didn't start clapping too. Now, you do!

My first recollection of such a thing was at a PD Day, probably around the mid-eighties, where we assembled to hear an American speaker. He was very good, lively, funny, and well-rehearsed. At the end, when we clapped our appreciation, he clapped too. I took it to mean that he was applauding us for being a good, attentive audience.

It worked then, but I don't always know what it means. In the case of Dance, were the choreographers clapping for themselves, the audience, the program in general, or were they simply going along with the celebratory spirit of the occasion?

While I don't mind the new fashion at all, I wonder when, where and why it changed. And in some cases, what it means. Or are my memories faulty?