Not your normal cardiac question: What could possibly be the physiological, well, logic behind my reaction?

I have thought about it many times over the years, and have never made sense of what my heart does. 30 years ago, i had the pleasure of meeting a girl that over the years has become my best friend. The first time i saw her, my heart started pounding in my chest, (typical reaction for a teen). However, to this day, i have the same physical reaction every time i first see her,(i can hold a conversation with her without this happening, however, if she should leave the room, or my attention be drawn elsewhere, it happens again upon seeing her ). I should note that this has never happened for any other reason, including time(s) that i was shot, stabbed, in major auto accidents, struck by vehicles, etc. What, in all seriousness, could cause such a reaction? (And yes, this is a straight, honest, and serious question). My own curiousity is really getting the best of me on this, and i figure that this is probably the only way i will get an answer to this. Thanks to all in advance.....willi