What are you looking at?

Something odd occurred at work the other day and it has been on my mind ever since.  I am hoping that writing about it will give me the needed closure.  One of my female co-workers asked me to come by her desk and assist with a report she has having difficulty formatting.  I stopped by the snack machine to grab some chips and proceeded to her desk.  When I sat down, she turned and looked at me to acknowledge my presence.  She quickly turned her head away.  She looked back at me smiling and turned away again.  She then asked me to leave her desk for about 5 seconds and to return.  I gave her a "What the hell?" look and walked off.  At this point in time, I was trying to determine what happened to cause her reaction.  Did I have something in my teeth?  Was there something in my nose? Did she need to adjust her clothing?  Many more possibilities raced through my mind over the next few minutes.  I returned to her desk and asked if she was ready to look at the report.  She said yes.  I asked what caused her reaction.  She told me that for some reason when she turned and looked at me, she started thinking of me in an inappropriate manner.  Do what? We work together everyday.  What about that particular moment in time made that thought cross your mind?  She later explained it was just something that came over her - no rhyme or reason.