My new WRX has about 750 miles on it now, with about 250 of those miles run with 89 octane fuel in it. The stupid part is that I KNEW it's supposed to get 91 octane (minimum) and that's what mid-grade is in Buffalo where I'm from. But here in SC, mid-grade is only 89! So the first time i fuelled up, I just grabbed the middle nozzle without even checking the octane rating. I shouldn't experience any problems after having done this correct? Once I realized what I did, I filled up with 93. Will this effect the ECU's learning process? Any tips/reassurance would be great.