Before getting too worried, try the 'cure most ills' solution to iPad problems by completely powering the iPad down and then powering it on again. To power it completely down, rather than simply putting it to sleep, like most people tend to do most of the time, you have to press and hold the Power button until the slider control appears asking you to confirm you really want to switch off. Once it's completely powered down, press and hold the Power switch again until the Apple logo appears and wait a few seconds for it to power up again; it plays a little 'jingle' just before the power up is complete.
Apple recommend you do this once a week in any case and it's known to cure a whole load of problems.
Tim