My first thought, naturally, is neglect. Your coach feels neglected, and is pouting. Alpines need love too
But seriously. When was the last time your hydraulic oil & filters were changed? If you have skipped the regular time-denominated oil changes (because mileage was sooo low?), you may have salt-laden condensation in the hydraulic reservoir (engine crankcase & maybe tranny too, and maybe the fuel tank if you didn't completely top off before long periods of storage). Once you kick the coach on, get hydraulic oil flowing, add a little heat, etc., the gunk may be accumulating in the reservoir & clogging the filters, or worse- flowing thru the system to the Bosch Hydromax Brake Booster in the front of the coach under the gen slide cap. You may be able to check this by opening the hydraulic reservoir @ rear engine hatch. You may want a flashlight & mirror to make the inspection easier.
You will want to download the brake system manuals. Alpine Coach Association (ACA), in response to WRV's closing is assembling a Technical Library. Go to the ACA website & click on ???, then scroll down for Chassis stuff & look for Brake, ABS & Brake Troubleshooting info. This site is under construction as we speak, so check back periodically if you don't find what you want. Also, since we depend on each other, post your further experiences w/the brakes here on iRV2 including links to any additional tech materials you may find while plumbing your way thru your specific problem(s). Good luck & let us know what happens. Mike