Mine will do that frequently (but not always) and it is for exactly the reason you suggest.
There is apparently a smooth enough flow on top of the sand bed that, I believe, allows a fine "covering" of dirt and debris to form and restrict the flow.....thereby increasing the psi.
It must be a very thin, uniform layer because when I shut of the pump, that abrupt stoppage of the flow loosens that fine layer and allows the water to pass more freely when the pump restarts.
It could also be loosened or disturbed instead at the time the pump restarts which might make more sense but I do see that often with my filter.