Thanks Chilli. Yes, they don't get stuck inside. We always keep doors open, even when it's raining. Luckily, I work with a lot of animal lovers too. I don't think they would want ta kill 'em. They'd just hope they didn't eat too much.
This guy [rat] did though, I think. He was really really fat. Of course, I suppose it could have been a female about to give birth or something.
About 3 weeks ago, I saw a mouse, but it was actually in my office. That was the first time in like 10 years i'd seen one inside anywhere. But he was really small and cute.
Perhaps the one i saw today was just a huge mouse and not a rat. I don't really know the difference.

How are your cute babies doing? Is the masked one still a little shy?