Doubtful. Even the oldest iPads are not old enough yet for battery life to become a problem. Even when batteries start to deteriorate (after about 3 years of charging from 0 to 100% every single day) the time taken to charge should not alter appreciably.
Which model do you have? If you are using it while you are charging it, it will take longer to charge, especially if you have your screen brightness turned up. I have the iPad 2, as in non-retina display version, and with the brightness at 100% and using a GPS app, the charger only just keeps up with the battery draw.