I've noticed something keeps happening: when I bring a button in from the design gallery and I change the text on the button from "button" to "click here" or whatever, the text is no longer centered in the button. When I check the Mouse-Over layer, the text is also misaligned. When I go to center the text on one layer, it then gets misaligned on the other!

The only way I've found around it is to make the button in a new document and then cut & paste it into the web page. Is this what everyone else is doing?