Definitely poop with some built up fur. Poop doesn't always look the same.

Since the original issue was resolved I have a couple things here that I am worried about. If you could answer these questions for me, I would really appreciate it.

What size tank is your snake in?

How old is your snake?

Are your ball python and corn snake in the same cage?

What kind of hides do you use?

What substrate do you use?

Is there anything directly hooked up to the UTH to control it? You said thermomete, which I'm guessing you mean a thermometer, which reads the temperatures themselves. You need some of those to know what temperatures are in the cage, and you also need a thermostat which is what is hooked up to a UTH to control it. Sometimes, you can also use rheostats.

Feeding a day early would not be an issue at all. Many people feed ball pythons every 5 days or every 7 days. Either is acceptable.

Thanks, and best of luck!