While passing another vehicle up a grade (55-60 mph) in drive the trans went into auto-stick mode by itself and I had to manually shift back into drive. It was as though it was stuck in second (2 was shown on the instrument cluster) and was reving at 5600 rpms. This is the first time I experienced this, the trans usually downshifts to pass and then resumes the proper upshifts when you decrease the throttle. I thought I was going to blow up the engine, I believe I was at the rev limit for 2nd gear. Anyone experience this?