firstly, welcome ;-)
I recommend you check the pressures again, the system should automatically reset after a couple of miles of running.
but since you have manually reset the system, it indicates a tpms (tyre pressure warning system) fault; and depending on the age of the car this would be an mot failure.
so yes take it back to the dealer, to sort out.
Maybe a duff tps valve on one of the tyres - that's what happened to mine. Fitted a new valve and no more warning light
If the light was on from day one, it's possible that someone changed a tyre and put a standard (non TPS) valve in. My local tyre dealer won't touch TPS valves and when mine develooed a leak, they put a standard valve in temporarily until I got around to getting a new valve from Ford when the car was next serviced.