Unanticipated Buttons

I had a weird button-pushing experience today at work. I had a question for my boss so I waited in a cubicle across from her office so I could catch her when she came in. My cubicle is in the floor below so I couldn't spot when she was in from my desk. She's terribly busy nowadays, so my motivation was to query her and go about my day based on the answer. Well, she was not happy with my action, telling me that she did not like being ambushed when she arrived at work. I was shaken up as that was not my intention. From my point of view there was little difference between waiting for her at that moment and dropping by later to see if she was at her desk then. The lesson learned? My wonderful boss has a boundary that I should respect. The reaction was not personal and I was not "at fault" due to my ignorance at the time. If I repeated the event I would be very much at fault. That's my take.