The charcoal and the clay CAN both reach a 'saturation point'...at some point. But it is not likely with just a bit of exposure, that they're saturated.
The worst possible case scenario (exposed to air in a very toxic environment) is that the charcoal/bentonite would no longer have any toxin-pulling "oompf", but the Bentonite would still be very effective for doing the 'sticking onto the mucoid plaque" and helping to pull it away.
What you're describing doesn't seem like much of an issue, and if it is, it's only a very slight issue :)