As mentioned by others above, it is either root damage or underwatering.
It is common but it is not the optimal condition.
I see many many well grown cattleya with many pbs all of which are plump. so old pb going wrinkly is not natural.
and you mentioned that your plant also had all of its pbs plump at the time of purchase.
Unless you are growing in the greenhouse with good humidity and good watering system, I find it nearly impossible to have all the pbs plump.
Do what Tucker suggested.