We put in wall to wall carpeting just about 3 years ago. Nice at first.
Slowly the wrinkles started appearing. This isn't a new phenomenon; we
bought a house 15 years earlier and it was only about 4 years old and it
had these same kind of wrinkles (as if the carpet just expanded in area or
repeated walking caused it to stretch) and we sold that house without ever
doing anything about the wrinkles (and the new buyers never said anything
about it, either, but it would be something I'd want to fix).

So, if there isn't some "magic" cure/fix for this, I'm presuming that I've
got to find some carpet intaller-guy and have him spend, what, 1/2 to full
day of restretching/relaying the carpet (not to mention moving a whole
bunch of furniture out of that area [a bear of a project on its own]), or
else get one of those knee-kick or power stretchers and do it myself?

Yeah, carpet is over a pad about 3/4 inch thick or so.

Art S.