Is any one here having sensitivity issues using the 3 or 4 finger swipe for Mission Control?

Suddenly the 3 or 4 finger swipe for Mission Control is having major sensitivity issues...a simple, light swipe would bring up mission control each and every time. Now I need to put more pressure and a slower swipe for Mission Control to come up. I honestly don't think there is a problem with my Trackpad cause all functions work flawlessly expect for bring up mission control with the 3 or 4 finger swipe. This issue is only my iMac's Trackpad, seems to be working flawlessly on my MacBook. Is it possible I need to buy a new Trackpad or something I need to reset in my setting to get it working like it used to? Thanks a lot...