Sorry to be late to the party.
My wife (age 60), mother-in-law (85), and I (65) all got Moderna boosters back in August, 5 1/2 months after our last regular shots (Moderna for me and my wife, Pfizer for my MIL). We just went on the CVS website, gave our details (no lying) and were given appointments without any questions.
I had a sore arm for a day after one of the first two shots but no other side effects, but I felt fatigued for most of the day after the booster. My wife was the same. MIL had no side effects from any of the shots!