Recently I changed the vanity light in the bathroom. When I turned on the light I realized the breaker had tripped. I reset the breaker and all was fine for a couple days... the breaker tripped again. So I reset it and the same thing... 2 days later it tripped. I removed the light and can find no problem with the installation.. is it possible the fixture has a short from the factory. Why would it take 2 days for the breaker to trip

There could be an intermittent short in the fixture, could even be a light bulb, thou rare, I have seen a light bulb actually cause a short.

Or it is possible that there is a problem elsewhere in the circuit, and it is just coincidence that the fixture was change and the short developed.

Can you leave the fixture disconnected, or at least the switch off for a while to see if the tripping stops. That brings to mind, does the breaker only trip when the switch for this light is on?