Intermittent front disc brake issue

Gents,

Subject vehicle: 1967 Barracuda
Manual Front DISC brakes: ‘73 & up style

What’s been done:
Master cylinder replaced ~8 years ago
Front flex hoses replaced ~8 years ago
New front calipers installed ~1 year ago
I drove it all last summer without issue.

I drove the car last night for the first time since July 2021 and the front brakes were dragging. I pulled the brake pedal towards myself and pumped the brakes several times and all seems well.

I’ve heard of OLD front flex hoses causing this but they were replaced ~8 years ago.

Any ideas?

Graham