I finally noticed that I "cheat" with almost every kick. I take a tiny step forward with my front foot before I turn for a roundhouse kick, spinning kick, back kick, whatever. I never even noticed, but my masters both do...
That's something to watch out for in poomsae too. Without realizing it, people often take a tiny step forward with the front foot before stepping properly with the rear foot. In poomsae, it also happens with kicking too: people take a tiny step forward with the front foot before kicking. In fact, now that I think about it, maybe that's another benefit of learning good poomsae: it teaches you to eliminate that tiny step.
Next time you're doing poomsae, check to see if you're doing the tiny step there too! I sometimes tiny-step, but I fight against it mightily.