Check Engine Light On?...Hoon it off!

So two days ago my check engine light comes on in the Mazda (not my car pictured above). I go to AAMCO for a free scan and they tell me it is one of those emissions sensors that does't effect drive-ability. I make an appointment to go to the dealership on Friday to have it checked out further. This morning I was fortunate enough to leave early in time to to to my favorite bagel shop for a sandwich and take the back roads to work (usually take the highway). There is a particular back road that runs parallel to the bay with several sharp turns. I have a nice spirited run and as soon as I exit the last turn...the light goes off. In reality I think it had something to do with the fact that this morning it was only 25 deg and not 2 deg....or it could be something else that is totally weird but hey, light went off.

So that's not helpful...

...I come out of work, start the car ('10 Mazda 3s 6MT) and the check engine light comes on. The motor did struggle to start this morning and nothing "felt" strange on the ride home. I saw that my antifreeze was a tad low so I topped it off. Could it be just the cold? If the light is still on tomorrow I might take it to AAMCO for a free scan. You guys have any thoughts?