Did you replace the rear seals with the rubber seals that have the circumference spring built into them? I have found that these are the best rear bearing seals, but they do give up over time.

Bearing Buddy makes a "Spindle Seal" which is a seal with an additional o-ring and a shield. You can also convert to EZ Lube axles which eliminates the pressurized hub issue and keeps your bearings full of new, fresh grease.

Thanks guys! I think i will pull the trailer over to McClain and have them check everything.