Why has our two year old chocolate lab started soft whining?

Our lil pup has been happy and traveled quite a bit with us over the last two years. She's very adaptable and loves adventures and meeting new people. A month ago we moved cross country from Southern California to outside of NYC along the Hudson River.

The first few weeks she was excited about new sights and smells but had some trouble adjusting to not being allowed to go out to the yard whenever she wants. (In California she had free reign of a large garden - here we have a smaller unfenced yard). This week she's started sad soft whining while hanging out at home. She does it while she's laying down in the living room on her bed, hanging out in kitchen while we make dinner and sometimes looking out the window.

At first, we thought it was in response to wanting to go see squirrels in yard but ruled that out. It's also not separation anxiety as it happens when both my fiancee and I are home. She's currently going through her heat cycle but has no other potential health concerns. She goes for walks daily, is making new pup friends at a local park, and some hikes on weekends. Would love any suggestions on why she might have started this new habit of whining.