It was not a nightmarish figment of my imagination.
After calling the number on the note, I found that, no, there is no one from the store residing in Cartersville who can do bike mechanic work out of their garage. In fact, they're closing their original Rome location to move to a larger store on Broad Street.
At least the Cartersille closing doesn't signify economic difficulties (which I was most afraid of). I guess they're going to just move the bikes from here to there. Now the closet bike shop to me is 26 miles away in Acworth.
I can only comfort myself with the old Episcopalian(?) saying, "In desolation remember consolation." Perhaps a new bike shop will spring up.