Not odd at all. I'm similarly most comfortable on bikes with much shorter top tubes. I might add that if your body proportions are such that you are most comfortable on a smaller bike than what someone your height normally would ride, you might be a good candidate for a custom frame. When Specialized, Giant, Cannondale or whatever manufacturer design a bike of a certain size, they do so with a certain height range and proportions that are with a standard deviation or so of the norm in mind. When we try to stuff a square peg into a round hole, we end up distributing weight on the bike in ways other than what it was designed for and screwing up the way the bike handles.

I recently had a custom frame built, which has a 55cm top tube, and 59 cm seat tube. On my old bike, I could never take my hands off the handlebars or get in the IAB position, holding my line while reaching for my water bottle took ever bit of concentration I could muster and I always had to take corners slower than other riders. I blamed these things on my own bike-handling skills, but as soon as I got on a bike that fits, I instantly discovered that I actually have pretty freaking good bike handling skills. The difference is night & day.