Why Prime Minister's Bodyguard was curiously staring at me all the time ?

I was sitting next to a friend ( old gentleman) who is also a long time friend with the PM. I noticed when PM came and sat few chairs away. PM's personal security officer came stand close to me and was staring at me only,( i was talking to my fried ) he could hear on earpiece. Then moved and stood at the door facing us but he was still staring at me. so I stared him back to check , so he looked away. Once PM finished addressing then I stepped in to talk to her, she closely looked at my face for 5 sec ( as we met second time in almost a year and half) and hand shakes with me with greetings, had few smiley selfies. Then PM walked through to have group photographs outside the building with others members , I did not follow.
My question is why the PM' personal protection officer was only looking at me so curiously. Has he been briefed about me previously, I felt he knew my face very well.
I am an ordinary person but I noticed most cabinet ministers and members of the parliament know my face if I am around they look curiously or stare twice 5/10 second. Have I been introduced to them privately.