Congrats to your DS on picking up a sideload scholarship. He was awarded one, and now that scholarship needs to be activated. Likely to activate he'll have needed to pass the physical test on day 1 this semester and then his university has to activate it with signing off/ processing the p/w.
Once activated the tuition will be paid, until activated it will not. We've seen in years past activating take some weeks but then book/ bi-monthly stipends are retro-paid and the semester tuition, fees are paid as well. No, this is not unusual/ unprecedented but your DS should take the lead to confirm all is OK.
I would recommend you or your DS confirming with your bursar's office at his university that you are OK while this is processed. And I do think your DS should take the lead to ask his chain of command what the timeline/ process is for the scholarship to be activated.
Hope that helps / good luck.