I think it's pretty common. Last year on my DC's team a couple of kids were swapped between the first and second teams. This year the coach has already stated that some changes are going to be made before spring. We can all sort of guess who it will be.
When it happened last year the players being moved up/down were told, but there was no announcement made to the team. Everyone just kind of figured it out based on who showed up to which practice and when they saw the changes to the roster in the app.