Thank you all for your responses! They are quite helpful!

I noticed this morning that this little bird was building a nest right above the window (below the roof). Last night, it was probably trying to fight the "enemy", by attacking its own reflection in the window - that's the most probable explanation.
My trip goes through St.Louis and there is always some kind of a road construction going on - so I am counting on a delay...I just hope it won't be a long one.