The "Inner Plate" is held in place with a special metal trim ring. When you looked at the inner plate, how was the outer trim ring? Was it fully secured or was it loose on one side?
My one lotus cap had a bent/warped inner plate, but it was working fine. It's not until that trim ring comes loose that you have problems. Sadly, the inner trim ring and inner plate are specially installed at the factory and cannot be replaced by the customer.
A cap will last as long as you treat it right! It seems going high in temperature or improper torch control can kill the cap, but in terms of durability, it should last longer than you if handled properly!