Don't blame you for freaking out. Agree with everyone else about it being a caring gesture, and letting her know if that's not OK.

My male boss kissed me on the forehead to comfort me about the London bombing happening back home. Totally unexpected and freaky, but at work and in front of everyone. He is a very touchy feely person and I'm learning to just take it as comforting. I even hope for a pat on the back now!!!