York Diamond 80 Bad Pressure Switch?

I came home to no heat from my York Diamond 80 (P4HUC20N09201A - upflow/horizontal) furnace. The diagnostics control was flashing 2 red lights which the manual indicates is an issue with the pressure switch: "This indicates that the normally open pressure switch contact are stuck in the closed position. The control confirms these contacts are open at the beginning of heat cycle. This would indicate a faulty pressure switch or mis-wiring." I found the following thread (http://www.doityourself.com/forum/gas-oil-home-heating-furnaces/157768-furnace-not-coming.html) and tapped/smacked the pressure switch a few times and the furnace fired up and it is working fine. I read several threads on various forums that indicate the pressure switch is rarely bad. Should I replace the switch or wait for it to happen again (e.g. assume anomaly?) If so, where do I get the part number from? The previous owners documentation is from Source1 HVAC Service Parts but it is of the P4DN series (not sure why they have that if the furnace is P4HU...). Thanks for help in advance.