When you squeezed the piston back on the first brake job, you may have sent some rusty fluid into the ABS module and now one of the valves in the module is stuck.

You can diagnose this. Pump the brakes a few times. Check the suspect wheel to see if it’s dragging. Now crack loose the metal brake line BEFORE it turns into the rubber section of brake hose. If the drag frees up, the problem is in the ABS unit. If the drag is still there, it’s the rubber hose or the brake caliper.