I replaced a light bulb in November/Dec 2020, and it has already burned out again. Looking for help identifying root cause before purchasing replacement (and/or is there a warranty on the light bulbs?). 

Bulb, 120v 300w Flood (br40fl300) 
Item# 3520-01A


More details - set of 3 lights, all on same circuit. The other 2 have not burned out yet in the 2 yrs I have owned the pool. The GFCI is not tripped, and we use the lights maybe 2-3x/month for 30 minutes at most, so the new bulb shouldn't have more than a few hundred hours maximum use since installation. I also replaced the gasket as instructed at the time.

What else should I be looking for to be sure there isn't an underlying problem with this specific light which is 1 of 3 on the same circuit?