Running every once in a while means plumbing system has lost just enough line pressure to close the pressure switch on pump and pump cycles.
Could be a very small leak/drip
Could be the internal check valve in pump leaking back to fresh water tank
Could be city water connection check valve drip
Could just be the change in pressure from water heater as the water heats and cools a bit (water expands/contracts when heated/cooled)
When it runs for a couple of seconds before shutting off then you have a leak.
A short burrrrup......good luck locating that source.
