Hi Kate! :wavey:
I see by your last posts that you were worried about this a few months ago as well, right? And then she went on your bed? Ugh...I've been there! Yuck!
What kind of substrate are you using? Only my little guys are on paper towels, so that makes it really easy to find the waste. The others are on aspen and that presents a bit more of a challenge. Aspen seems to absorb the moisture, so I'm left with a dried out clump of poo that looks like it's weeks old when actually it can't be more than a few days old. I also use thick substrate so they can burrow, so digging down into four or five inches of aspen can make it difficult to find it. Because of that, I change out half of their cage weekly. I scoop out one side entirely and clean it with vinegar/then water rinse. I replace the aspen, and then I remove any waste I find on the opposite side, spot clean as needed, and during the next week's maintenance will clean that side. Then every 6-8 weeks I clean out the entire thing, disinfect, etc. So to make a short story way too long, it's possible it's becoming dried out in the substrate, and depending on what you're using, you might not even see it. Don't be afraid to just scoop some of that stuff out of his cage. Maybe while you're feeding him in his bin go in and search around. If he's still eating, chances are good he's also pooping.