So since yesterday, I've put a little over 40 miles on it, all city driving. The light has not come on at all even at idle. I still don't believe the oil was the reason since I actually went back to a lighter oil, but we'll see how the next few weeks goes.
I'm still going to change the sensor because I already bought it, and theres really no reason not to. When I was trying to find it on the motor yesterday, I was using the wire loom as a guide when fishing my hand down in there, so maybe it is going bad and messing with it did something.