I have a 23 month old BLF. She and I were sitting in the living room tonight watching football. A neighbor (child) approaches the door (front door is open with a closed, full view glass storm door). The dog barked like I have never heard before; this was an alert kind of bark. It was deep and she barked multiple times. My wife heard her bark like this one other time when the gas man approached the back of the house. She was inside then as well. Should I be concerned or thankful? She has never been aggressive. As a matter of fact, she nuzzled up to someone she had never met this morning in the duck blind. What do ya'll think?