We had to replace our rear axle after 3000 miles. The tire on rear driver's side was essentially bald on the inside and the trailer was dog tracking pretty bad. We could see where the axle was bent (yes, I know it's supposed to be slightly bent in the middle).
Dexter sent us a replacement axle (3500#), at no cost, but we opted to have a beefier axle custom built (the Dexter axle is collecting dust in our garage).
We are certain that the bent axle was a result of our super spread axles - 15" between tires.
kinggartk - do you have spread axles as well?