Mine did that on the way to the Nor'easter and I figered it was my load wasn't balanced. I don't know what speed it was though, so I tried it on the way home and it didn't do it. I try it now every so often and it hasn't done it since. I don't have the answer for ya just the fact that mine has done it and now it don't. Keep us posted on what you check and what cures it when you find it.
