Wheel Bearings on a 7 year old pop-up - Shuld I?

I own a bunch of different trailers and have not even repacked bearings much less replaced in years. I do jack the axle and wiggle the tire to check the amount of play in the bearings when my IR temp gun shows it's hotter than the other wheel bearings. If it's got excessive play I'll tighten when I pull the cap off to look at the grease. If the grease is old and hard I put some 90 weight gear oil in the cap and put it back on quickly. Only been doing this for 40 years. Your mileage may vary.