This makes sense. I had quite a flinch and didn't know/realise it. It only became clear as I shot more.
I developed a flinch/snatch seemingly out of nowhere about 5 years back and it only affected handgun and then only when shooting fast. Rifle, shotgun and slow fire pistol were unaffected. It nearly did my head in and I shot out >10k rounds in solo drills at the range trying to chase it down. Eventually killed it with 15 to 20 minutes of dry fire drills 5 days a week. Took a month or so and touch wood its still gone.
As per JamesNotBond's comment I think that the static and dynamic skills of shooting aren't equally durable. Also the stuff that you can think through and concentrate on while firing slowly and deliberately like stance, breathing, sight picture, trigger control, follow through and so forth aren't everything you need to shoot fast or at moving targets. The latter skills degrade fairly quickly for me and require constant brushing up.