Potty Training - Day 32

I thought we were in the clear. She did awesome for the first 2/3 of the day. She got two pees and a poop in the potty, amazing! But THEN she pooped AGAIN, in her pull-up this time. I can't even describe how disappointed/upset/annoyed I am. All the books/websites I've read say don't get upset at them when they have an accident. I didn't yell at her or anything, but I'm sure she could tell that I was far from happy. I feel very badly, but I just couldn't hide it completely. It's just that she was doing so well! And now that she's reverted, I'm afraid that all our progress will go right out the window. I'm sure it's an irrational fear, though. It happened when she was outside playing with her dad, so she was distracted and not near the bathroom. So I just have to calm down and remind myself that setbacks happen (every says so), especially when things are more exciting/different.