Probably way too late to be of interest, but since I saw only one reply, I thought I'd respond. Mine did this when I put slightly larger rear tires on. Initially cruise would work only at lower speeds and for several seconds. Over a few weeks of very light use, it steadily improved to fully correct operation. It makes sense; I'm just glad the car is smart enough to learn and correct.

That was a few years back. Now the cruise control is dead from some other issue I believe to be unrelated. Wiring damage (rodent) or water damage from a horrible road trip. More to search before I start asking questions again.

Merry Christmas.

Michael, black 05 Roadster, 6spd Limited