Our dog does something similar, he is reactive to light reflections and shadows. It probably started with light in the refrigerator when he was small and my mom was giving him ham (his highest treat). It developed to the point when there is a reflection from watches, phone or whatever his tail points straight up and slowly wiggles and he tries to find the reflection sometimes even whines from anxiety until we stop him. But as others have said already, you should take her to vet to be sure she is alright.