Unknown Blood Spotting

I'm terrified. While I was deep cleaning my chin cage, I found some blood on top of their hay feeder. There's no signs that they fought, they still cuddle, and no fur slip. I'm not sure when exactly the blood happened, but somewhere in the past 12 hours. They're acting normally too. They're going to the Vet in 4 weeks. Can it wait that long, or do they need to be seen now? No other blood has been spotted thus far.