"About time you get your hands dirty and DIY."
Nonsense, some people have no desire to "get your hands dirty" as you put it. That's why they have shop or a mechanic take care of it. Perhaps they've tried it before and decided they didn't like it and didn't want to do it. Not your concern as that isn't what he wanted to know anyway.
I notice the higher temperatures are both on the same side, maybe sun shining, which will definitely raise tire temps not sure about wheel bearing. Also could be the crown of the road was loading one side of the trailer more than the other.
You say recently, but recently can be anywhere from 6 weeks to 6 months to a year. If you don't wish to do it yourself, have your shop/mechanic check the bearing freeplay. If he says it is okay, then carry your temp gun and check the wheels periodically while on the road.