Estimated speed on ride seems to be off

For the first time on a ride my speed seems to be off. I did a ride I had done prior and on a long climb of avg 9% and having the same approx. power avg output, my time was 20 % faster. I checked my weight setting post ride and it was ok. This is on the 7.0.6 version. I had ridden last week and all things were ok.