Consume Don't Think

We went on a quick trip to the Harz Mountains and ended up staying at the Achtermann Hotel in Goslar.. We took Poppy out for an evening stroll in the city centre. I was shooting random photographs with the last available light when this graffiti and the windows caught my eye. I fired off a couple of frames. I remember looking at the black windows and thought they may contrast well with the white spray paint text.

Later I checked the images and noticed something unexplained in the bottom right corner of the window on the right handside.. Strange... For a detailed closer look of both frames see here

Whatever it is/was it appears to move.. It definitely was not a reflection of something/somebody in the street and when I took the shot I most certainly saw nothing/nobody behind the glass looking outward...? It's very rare i take an image and find something unexpected later at processing stage and on this occasion I have and the feeling is not very pleasant.. Any suggestions to make me sleep easier would be gratefully appreciated