Why Did I Do That?

So there's this guy at my local bookstore who is always reading these dusty old books from like 1900 or something. He wears glasses that are half prescription, half magnifying glass, and his hair has been tied into the same topknot for years. You know the type - he’s definitely not a hipster because those went out before grunge was even a thing. Anyway, last weekend, I’m sitting at one of those cafe tables reading this really boring self-help book when all of a sudden I have this uncontrollable urge to sneak up behind him and spray his chair with silly string. Now, I'm not saying I did it (because obviously that would make me an awful person), but let's just say I didn’t leave until my nose was tingling from sneezing. I mean, why? He’s a complete stranger who has never acknowledged my existence or even looked at me the wrong way. It wasn't as if I thought he had offended me somehow (although that would be hilarious to think about), it just...happened. Now, I know this is probably the worst thing anyone can do in an actual public space - you know how hard it is to clean off fabric nowadays? But something was just pushing me. Could it have been because he looked so ancient and out-of-touch that day? Was it boredom driving me towards a momentary act of mischief? Anyway, I’m worried now every time I see him there with his books and his silly glasses and his long-forgotten topknot hairdo...he’s probably the least likely person to ever notice something like this, but here I am, wondering if he did. So, tell me: Am I being too paranoid? Is this a weirdly common thing for someone my age (57) to want to do? Should I just write him an apology letter or would that be more suspicious than the act itself?