My car jerks when accelerating?

I just started experiencing this problem yesterday. I drove for about an hour between my old home and my new home and then as soon as I got off the beltway for some reason when I would press down on the gas pedal, my car would jerk a bit. The engine didn't turn off and the car kept running, but for some reason everytime I would hit the gas pedal (wether it was hard or soft) the car would kinda jerk. I left it parked outside overnight and just took it for a test drive not to long ago and now it seems to be working just fine. I'm kinda confused about what could've caused that issue last night and I'm supposed to be doing a lot of driving in the next few days. The last thing I want is for my car to die out on me in the middle of the highway. I don't really have the kind of funds to fix a car right now that has any severe mechanical problems. So I was just curious as to what this could possibly be. By the way, the car is a Saturn Ion 2006 model and it has over 120,000 miles on it.