How would you really know it was the cap though?
Also are you *sure* you know it is one mic and not the other? My ADKs have big serial numbers on the bodies, I always set them up with the lower number left. The serial numbers on my Gefells are so small, and on the end too, that I never bother, although in retrospect I may now put a piece of gaffers tape to mark one in case I start having problems.
But I have a really old pair of the black ones, not the silver ones. Yours may be different.
If you have some system where you know for sure it is always mic 1 and never mic 2, and you never swap the caps and bodies, you could try doing that now. Assuming you keep track of it, and it happens again, you might then at least suspect it is either one specific cap or one specific body that has the problem.