I doubt you have a problem. The tranny would be more likely to slip on take off than cruising down the free way, and the cam would have no effect on the RPM at all.
Would you happen to have been in a daily driver for a while that is an overdrive? I find you get used to the current ride, and all previouse things kinda fade...my observations anyways.
If you have a 28-ish inch tall tire with 307 gears, you should be doing about this;
Or this if your having fun;
