I just brewed a Centennial Pale Ale...8lb 2-row .5lb C60, S-05, OG - 1.040. So, I realized that I had made notes to do Centennial 9.9%, .5oz @60, .5oz @15, 1.5oz @0. What I actually did is 1.5 @60, .5 @10, .5 @5. Oops...I was wondering why the hops smacked me in the face from the hydro sample. I hope this doesn't suck.
Maybe you can just call it a Centennial IPA now, and play it off like you made it that way on purpose.
Another thought is you might want to try dry hopping after a week or two to increase the hop aroma to be closer to what you intended for. I am not sure what amount of hops would be best, but since you meant for 1.5 oz @ 0 min and actually did .5 oz @ 5 min, you could just dry hop 1 oz after 1 week in the fermenter.
Dry hopped with 1oz 6.2% cascade for about a week. LHBS was out of centennials. Gravity at racking to secondary is 1.004, giving me about 4.7% ABV. It is fairly bitter, but not as bad as I feared. I'll know more in a few weeks after bottle conditioning. I might name this one Happy Accident..