I saw Shibby today on the way home from work and he told me about his CEL across the intersection of Wilmington and Dorothy. I didn't tell him, but right after I left the intersection I remembered that he just did exhaust work, and my CEL for Cat Efficiency didn't come on for a good 500 miles after my install. I shoulda told you that, but my brain wasn't quite in gear at the time.
I wouldn't worry about it, I had my CEL on for like 4-5 months till I got my AccessPORT to clear it. You'll be just fine, and you won't have to worry about getting bad gas mileage or whatever. It doesn't make a difference.