Saw something at my neighbor's empty house.

My little dog got out of the yard and we tracked her to the nextdoor neighbor's back yard. I thought that house was abandoned. But I saw two reflective running shoes moving around by their sliding glass door. It creeped me out. I never see any lights on at night. The owner is a widow who lives with her daughter about 300 miles away. Should I go over there and apologize for entering their property? I feel like I should just forget I ever saw it.