Did you change humidors?
Do you have less cigars in than before?
Did you change the location of your humidor?

I'll assume you sized the beads for the volume of your humidor.

Is there something mechanically wrong with your seal?
I'd assume in Miami, it's not cold enough to warrant the heat being on (if ever)

The short of it is, if you've been using them with distilled water, they're not going to wear out.

Will