That's exactly what happened for me too. I got Scottie when he was 5 months old. A month later I had a one-week vacation. The only person I'd trusting leaving him with is my mom. Prior to leaving, I made sure they got to know each other because Scottie is a very timid little guy. And of course, I had to 'train' my mom on how to take care of him.
It was probably more traumatic for me than for Scottie. I got my mom to facetime me every night!
My mom loves Scottie though because she misses having a dog around the house and she LOVES dogs.