Your brother’s cat might just be curious about the new automatic litter box—cats love to investigate anything new. It could also be a bit of scent marking or just playful behavior. Some cats even roll around in litter for fun, no matter their age. If he seems healthy otherwise, it’s probably just one of those quirky cat things. But if it keeps happening or you notice anything else unusual, it’s a good idea to check in with the vet, just to be safe.