NBA Mechanic? crossed wrist clapping?

[Jimgolf]

I was watching an NBA game the other day, and with 23.5 seconds on the game clock and about 15 on the shot clock, the trailing official gave a signal to the other two officials that I haven't seen before. After crossing the midcourt line, he started chopping one wrist over the other, (almost like clapping), with both hands in fists, 6 or seven times. I've never noticed this mechanic before and was wondering what it meant. My guess was something to do with the shot clock being turned off after the possession ended.