Gauge light started blinking

That usually means you have a problem that is serious enough that you should check on it. Like low oil pressure, high coolant temperatures, alternator stopped working. What did you see when you looked at the dash? Any odd lights or gauges out of the normal ranges? Any odd noises or smells?

Oil could be a bad oil pressure sending unit or switch, or it could be something more serious. Check the switch for oil leakage. They can fail and generally they do not leak a lot. On the 4.3's the oil lines like to fail and leak. The gasket between the filter adapter and the block fail. Check your oil level and then look around the engine compartment with the engine running. Look for oil where it should not be.