No , I don't think it is normal. A few factors to consider are as follows:
-Do you leave your
batteries or ProVari in a hot location such as in the car for long periods of time?
-Do you have more than two batteries in your rotation?
-If you are letting them fully discharge every time before charging,you could be putting undue stress on your batteries.
-Finally, check the charge state when they come off the charger as it is possible that your charger is defective.