While you were on your Alabama/Orlando trip, did you roll over or against any curbs or hit a big pothole or ??? Tires can be damaged and axles can knocked out of alignment when that happens-very hard on tires.
Did you load your 5er differently on the 2nd trip? Perhaps you had a lot more weight on one side-perhaps the tires were overloaded and heated up.
Tire pressures are important too. It seems odd that one side would be OK but not the other, but maybe the sun was a factor, or maybe ??? - Something you can ponder.
Hope that helps.