1962 Ford Falcon breaks grabs one side premature

Hi.
I have an odd problem.
Been doing brakes myself off and on for many years.
Im restoring a 62 falcon.
4 to 5 years ago I replaced all the brake lines.
The drums are scored just a bit, but the pads were new years ago.
I really dont put any miles on it so all has been working awesome.
Until right after this winter. Out of no where the dr side front grabs
first and locks up each time you apply breaks, until you pump it up
a few time for a minute, then its fine. Unless you let it sit again for a
couple hours. I decided to replace the wheel cylinders an ruff up the
shoes and drums with a little sand paper. I adjusted the shoes up close
to the drums, and also bled them, and the same thing still happens.
Its so drastic that it makes no sense to me. All I can think is for some
reason the drums are causing it, so Im going to swap them and see if
the problem switches sides. As I say, Ive had drums scored much much
worse and pads to the metal, and never had this happen?