Sticky brakes near the beach

I've noticed an issue with my brakes when leaving the beach, the most severe was after a week of parking ocean side. I tried to drive home but a small input on the brake pedal would lock up the wheels at slow speeds <10 mph. I was in traffic too and it was horrible. It only fixed itself when I had space to go ~30 mph and keep the wheels moving while braking. I've never had this on any other vehicle, what could cause this? Thanks.

2018 DCLB 86k mi
TRD-OR
285/70R17

 

It has been my experience that Toyota rotors have a tendency to flash-rust when exposed to damp environments for a prolonged period without daily driving. The rust buildup tends to make the front brakes "grabby" when first driven. They need a few miles with a few applications of the brakes to remove the rust build-up. Can sometimes result in faster than usual wearing of the rotors.