Dog alert when she sees other dogs/people near the house

Hi there! My husband and I rescued our 1 year old American bully Athena about a week ago. She came to us malnourished and scarred up from a pretty awful abuse situation, but she's already made so much progress in terms of putting on weight and learning how to live in a home where she is loved and adored. When she met us, our kids, my brother in law and even a few people at gas stations on her ride home, she was very calm and friendly.

My question is more out of curiosity than anything. I've noticed when Athena notices a person or another dog close to our house, she will perk up and want to trot over to them. Ears forward, tail erect, weight center-balanced, just overall on alert and intrigued by them. After a few seconds of curiosity she quickly relaxes and goes back to sniffing the ground for the perfect pee spot or playing with her ball or whatever she was doing before.
Does anyone else's dog do this? Should I be worried, or is it fairly normal to notice these things this way?