Wife and I keep finding dog kibbles in our shoes

Apologies for the wall of text below.

We have now found kibbles in our shoes 3 times. I can’t remember exactly when it happened the first time but it was within a few weeks ago. Tonight, we found a bunch of kibbles in one of her shoes and a few in one of mine. The hair on my body was standing on end and I felt so creeped out. There were no kibbles anywhere else nearby. My wife thinks rodents but I have no idea how they could get into the kibbles in the first place as they are pretty sealed in hard plastic containers. They would also have to bring a lot of food across the whole house since the dog food is on the opposite side of the house.

We have working CO detectors and it’s not like we have any gas running right now anyways since it’s summer. I was wondering if one of us was sleep walking and doing it but that would require us to go down really steep stairs and perform multiple steps.

I also stopped a medication, Wellbutrin, at the beginning of July so I wonder if I’m doing weird shit because of that.

Nobody else lives here either. We have basement tenants but there’s no way for them to enter the main floor, the stairs within the house are sealed off and the only way to get between the two units is to go from outside. We have cameras that I check regularly and I haven’t seen anyone break in and do that. It’s also highly unlikely we have a stranger living here because there’s no space for someone to hide and the attic is converted into a living space, which is where we sleep. One of our dogs would also go berserk if he smelled an unfamiliar person around.

Tl;dr - kibbles mysteriously getting in shoes. Probably not CO poisoning. Sleepwalking? Rodents?