Adopted a lab mix about a month ago and has not had any accidents until 2 days ago. She is left to roam the house all day and has had no accidents. The past 2 days she has peed right in front of us in a our den area. She does not have access to this area during the day, only when we are in that room with us. Why is she starting this now?

Has anything in her diet changed or her environment recently? How old is she?