EVERY YEAR AFTER WINTER STOREAGE, I "LOSE" MY BRAKE PEDAL. I HAVE TO BLEED THE SYSTEM AND THEN ITS FINE. OTHER THAN JUST SITTING, WHY????
I DID REPLACE THE L/F CALIPER A YEAR AGO, IT WAS SEEPING A LITTLE.

I used to have the same problem, usually because the car sat for long periods of time. I was using Dot 3 brake fluid. I eventually changed all my calipers and master cylinder and switched to Dot 5 silicone brake fluid and have not had the problem since. It is possible if the car is sitting alot that you get moisture in the system, something that the Dot 5 eliminates.

Reid '72 T-top

If you make the switch, remember to completely flush the whole system. Silicones do not mix with conventional fluids.

It sounds like you are getting some air past the piston seals. How old are the seals, and are the calipers Stainless Steel sleeved?

My 72 sat for 8 years with DOT 5 Silicone fluid, and the seals fatigued, I guess, and very slowly leaked out all the fluid!! I just replaced the pistons with VB&P O ring type, and still found some rust in the caliper piston cavities where the SS sleeve stopped! DOT 5 doesn't prevet moisture from entering, the fluid doesn't absorb it like DOT 3/4. So the moisture collects in little pockets. When I swithched from DOT 3 to DOT 5 I ran a gallon of denatured alcohol through the system to capture and flush out as much of any residual DOT 3 and moisture that I could.

I would look at replacing the seals, if not going to thge O ring type. They appear to be a more robust seal, although I'll find out as I use my car more.

Good Luck

Now matter what you choose, the best prevention is to flush the brake fluid at a minimum of every two years, and perhaps every year. One you repair your seepage problem this should keep it in good shape. It would alow help if you go out and press the brake several times every couple of weeks. Even if the car is stored on jacks, this is a good thing to do.