U30 Proto2000 truck flex?

[rkswp]

I recently purchased one of the new Proto2000 U30's with sound and was pleased with the sound & performance. When I took it for a spin around the layout I found that it would stall or derail on two curves. After careful inspection I found that the superelevation on the curves was causing a truck wheel to fly about 1/32" off the railhead.
Comparing to my other Proto, Athern & Kato locos I decided that the trucks had almost no sideways flex. The float along the loco axis was fine.
As the U30 was brand new I didn't want to take it apart and risk damaging it. The dealer didn't have another U30 in stock to compare against so I returned the loco.
Has anyone had a similar problem with the Proto2000 U30?