Stains on prefolds

SimoneSays22

I have a washing question. My DS dirtied a bleached prefold yesterday morning. I did a load of wash tonight. I have an older washing machine and it doesn't have a plain rinse or soak cycle. So I just washed it on a light wash cold cycle. I then added detergent and did a regular hot cycle with cold rinse.

When I went to switch the laundry, there is a stain on the prefold. Is that normal? I thought I was following the instructions. I guess it's not a big deal, since he'll probably poop on it again! But it seems like everyone else is able to get stains out. Should I have soaked it at all yesterday? Oh, and I EBF. Thanks!