Also noted pull to right
mhughett, you are quite right. There was pull to one side! It pulled to the right and the mechanic said the right front caliper was frozen. But is true, that once the mechanic heard that my steering wheel began to shake only after the car warmed up, that he jumped to the guess that it wasn't so much a tire out-of-balance as it was a frozen caliper. Why the frozen caliper would cause the steering wheel to shake after wam up is a bit beyond me.