Weird occurence with CEL

[NYBladeZ]

I recently installed the Meisterschaft full catback paired with my fast intentions long tube headers. Prior to, I had an uprev tune done by performance motorsport while I was running straight 2.5" tubing to the stock muffler. Upon installing my Meister, shortly thereafter the CEL went on. Using my buddies OBII reader (a cool $100 tool btw) we pulled up the code P0158. After a bit of researching it looked like a bank 2 sensor 2 error, I was running rich and it was causing the secondary 02 sensor, not the afr sensor to go off. I figured I was going to burn out the sensor and later on I'd buy a new 02 sensor and install it when I got a retune (if and when the HPS intake tubes arrive).

However, last night after filling up the gas tank I jump in and the CEL is still on. I ran home grabbed a few things, jumped back in and the CEL is OFF! I drove for about 30 miles and it remained off?!?! I used the OBII reader, it initially gave the stored trouble code, no additional codes, I cleared all codes and still haven't had the light come on. I can run another OBII reading after 200 miles.

Does anyone have a hypothesis as to why the CEL would go off? I'm not complaining, but I figured the tune hasn't changed, even after I did the pedal trick the light still remained on and it seems really weird that all of a sudden it would go off.