CM

I somewhat had this happen to me when I would have the car in drive (not in auto-stick). I have an SRT and I bought it with 85K on the clock. When really getting on it from a dead stop, sometimes it would go into "limp mode" which is when the car will shift into 2nd gear and not shift out of it. At the time, I had no idea that these cars even had a "limp mode". When I drove it normally, it shifted fine. After a week or so, it felt as if the tranny would slip when I would put my foot in it at about 40 MPH. I checked the service manual and saw that these cars needed a transmission fluid change at 80K. Since I am the fourth owner, I was certain that the previous owners drove the car like I did (spiritedly) and figured a fluid change was in order. I am not a good DIY'er so I took the car to a dealer. They dropped the pan and changed the filter and I asked them to back flush the torque converter to make sure that they got as much of that old fluid out as possible. That service cost me about $500, but after it was done, I have had zero problems with the car shifting.

I'm not saying you need a fluid change since your car only has 63K on it, but it helped mine. Just my $.02

Good luck!!

RL