I had a similar experience with our 2011 22FB and it is probably caused by improper tire pressure. This happened to me in 2012 and last year (2013) I watched the tire pressure like a hawk and had no issues. In 2012 I had to replace two tires because they were wearing off on the edges (one inside edge and the other outside edge).
I took all kinds of measurements looking for a bent axle and found nothing.
Get your self a digital tire pressure gauge and never rely on the gauges that air on the air hoses. They are notorious for being inaccurate. When Jayco says 50PSI that is what it means. No more (the tires are only rated to 50PSI) and no less. Since you have a pop up it probably uses smaller tires, but make sure you run at trailer manufacturers specs.
Hope this helps.
Jim and Mary B.
Retired Firefighter - 33 years
School Bus Mechanic[/COLOR]
2011 Jayco Jay Flight 22FB
2010 F-150 Super Crew Lariat 5.4 3.55