Nipsy drags his butt across the floor

I noticed Nipsy (3 yo long hair) pulling himself across the wood floor
with his front legs and I started to panic thinking that his rear legs
were paralyzed. I was already mentally driving to the emergency vet.
Then as I got up, so did he, and proceeded to walk across the floor
normally.

None of my cats have done this before but I've read about it and I
suppose this means impacted anal glands? Or at least something around
his butt itches. It looked normal and clean although a bit hard to
find through all that hair. No matting or "residue". Could be worms I
guess but that would be odd in the middle of the winter and I've
noticed nothing in the litterbox.

Oh well, I'll call the vet when they open. Inconvenient of course, but
certainly better and cheaper than dealing with the emergency vet and a
saddle clot. That scared the crap out of me until he started walking.