The valve may be sticking and may just need to be operated more frequently. Be sure to change the air filter/drier every two years to ensure the air is staying dry and you should not get sticking air valves. Lubricate the mechanical ride height valves with dry silicone when you lube the chassis. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7