While I haven't had THAT thought, I do have reoccurring thoughts, that I was sure I had gotten over, but they do come back sometimes.. I'm not sure if that's what you're asking though.
I've only really had OCD symptoms for about four years now, but when it comes to the thoughts, they come back sometimes, I think when I'm most vulnerable.

Absolutely normal to OCD. I remember stuff from the time I was 2 or 3 and I'm 40 now. As far as the feeling or fear that you've hit someone with your car...let me tell you my most recent story with that. We were coming home from a ballgame about an hour away..me, my mom and my daughter and a few other team members. We were going around a curve..and this car met us in the curve and had to get over to keep from hitting us. I knew in that moment that noone had hit anyone. Here's the clincher though.....we got a few miles up the road..and I began to wonder if maybe they had had to veer off the road after having met me on that curve...and maybe they were wrecked and injured and maybe even dead. I told my mom and I wanted to go back and check. She says to me, "Erica, if we had hit them..we'd of felt it or heard it....and if they had veered off..we'd of heard them hit the gravel." This didn't satisfy me.....but it made me feel so stupid that I didn't turn around. The only thought that got me through that was that I could call the next day and find out if there had been any accidents in that area. That thought calmed me....I went home and went to bed..woke up the next morning....with something else consuming my every bit of mental energy and the car was never thought of again.