Check the shoe adjustment. If that wheel is adjusted up tighter than the others it will lock up first.

Also check for contamination on the shoes themselves. If they somehow got grease or oil on them they will grab.

When you say "hot" are you referring to the engine or the brakes themselves?

If it's the engine, once it's warmed up it probably makes a little more vacuum so your booster has a little more to work with.

If it's a new/reman booster it might also have a calibration problem itself. There is a valve inside them that allows them to be progressive. I've had a booster that as soon as you touched the pedal it went to full boost and put your face in the windshield. If you have uneven shoe adjustment it would lock up one wheel before the others.

Kevin