SES light went off????

i looked with the search function, but i couldn't find an answer, so i apologize if this has already been asked, but i installed a BBK o/r X-pipe on my '04 with a Flowmaster cat-back. everything went fine after i got a little leak problem fixed. the SES light came on because i haven't gotten the MIL eliminators yet, but after about 1000 miles, the SES light went off. um....why? this isn't like a limp mode thing happening is it? my car still seems to fun fine, but how can the light just go off? the computer can't recalibrate for bad emissions can it? would that make my car run lean? oh, so lost. help please. i hate being a newbie.

thanks,

joe

thanks, guys. i just wanted to make sure i wasn't running lean or anything like that. i mean, a friend of mine has a 2000 grand prix GT (not GTP) and i had hid by at least 8 car lengths, so i thought i was running ok, but i am new at this. my old stang was a V6. ouch. i'll never do that again.

MIL's it is.

joe