this happened for a day only, confused the crap out of me too.

When I was in third gear after leaving work, I was accelerating away from there, and when I went to slow down for a coming up red light ahead of me, the steering wheel would shake back and forth a bit then stop when it got used to the deceleration. Me being me, I wanted to see if it would do it again, and it did. 3 more times at that. only did it in 3rd gear too, didn't in second, or 4th. didn't bother trying in first though.

I had just filled up BOTH front tires to 33PSI each.