He does act up a bit (just a bit) when he sees other horses, but mainly it's just wanting to go faster to see them, not wanting to pass them, and neighing REALLY loud to get their attention.
He's also really barny... and never really wants to get out of his stall, into the open air. :P
But I think it's kind of funny. I ride these horses, they're great horses, for beginners as well as for advanced riders, and then, after a few times of riding them, I suddenly realize that they're stallions! Out of the 20+ horses I've ridden... I think 2 were mares, and four or five were Geldings. All the rest were stallions.
Don't worry... he's a gorgeous horse with great bloodlines. I only know his stable name though: Koki (Koh-kee).