Unexpectedly High Efficiency on Brewday

I'm on my third batch of AG BIAB brewing and I had an unexpected 85% efficiency. I had been doing one-gallon batches, but this time I had enough grain and hops to make a 1.5-gallon batch. On bottling-day I tasted the beer and thought I had some bug get in and I had made a sour - the taste was sour-sweet, green, and not really good. After reading all these posts about how bad your beer tastes and 'just give it time,' I let it go. Two weeks later it was somewhat more mellow, but still had a really sweet taste to it and a bit of a bad aftertaste. Three weeks now and the bad aftertaste is mostly gone, but the sweetness is still there. I used beer calculus (beercalculus.hopville.com) and adjusted the efficiency from the default 75% to my 85%. It took my recipe from a solid APA to an under-hopped, yellow, malty-sweet accident (which is fairly accurate to what I now have). I'm not too picky so its still drink-able, but I'm wondering what I can do in the future...

I know I can adjust for next time, but what can you do on your brew-day to adjust for an unexpectedly high efficiency without sacrificing too much of your beer's flavor?

Most people would be happy as hell with an 85% eff

If you're going to overshoot your OG, you could take part of the wort out and save it, freeze it, make starters with it, etc and add some more water to dilute your batch. If you can keep your numbers up, just use less grain next time and problem solved.