My painter did 4 coats of paint! That is on top of walls being completely primed also. He said for some reason 2 coats was not working out well (due to spackling maybe). I am concerned that 4 is too much, unheard of. It is Acrylic water based premium Benjamin Moore paint.
Don't be concerned. Once it cures the paint will be fine. It isn't rare to need several coats to get perfect coverage. It depends on several factors; the new color, the old color, sheen of the new paint and its quality. Example is pastel yellows, well known as bad coverage colors.