It's worth having your pressure gauge checked out from time to time against a known calibrated/certified gauge. If its out at least you know how much to compensate by.
A simple check that is easy to do especially for the digital type gauges is one of repeatability.
Take three readings one after the other, are they all very close? if so, OK, if not, yer gauge is a random number generator
A mate did this once with his digi gauge and got readings that were 7 PSI apart. Tried a new battery and still the same, bin fodder.
Ray.