Q: Oil pressure light

My oil light came on about a week ago Thursday, and I took it in to check it out. The guy said that there is most likely sludge in my oil pan, so he cleaned that out a replaced a tube in the car. He showed me pictures of the before and after and I looked awesome! When I was driving home, my car sounded fine but the light was still on. He said it was most likely a light problem, but worst case senerio, there was gunk in the engine that wasn't drained and we will need to clean it again. He said that was worst case though. He said himself the car sounded fine. Plus, since he fixed it my light either flickers on and off, or stays on for a couple minutes, then goes away, then comes back, etc. should I be concerned or is it really just a light problem??

My car has 76321 miles.
My car's transmission is unknown to me.