Or has had a pregnant pet?
I got four female mice for my birthday and it turned out one was pregnant when I took her home! Now she's in labor and I'm really excited but anxious, too. I'm just grateful it's not a bigger animal having babies because that would just completely overwhelm me!
Side note: Once the babies are 2-3 weeks old they'll be going back to the pet store (we buy from a small store that treats their animals well and buys from good breeders so I know they'll be well cared for there).