I don't really use the button labels, I usually just make my own and insert them as buttons that don't do anything.  But I did open up an old file where labels were used and didnt notice anything out of place.  I also created a new button with a label and the label was centered.  Maybe 3.0 is more picky about how large the label font can be before it starts to drop letters.  That would be annoying.

on a related note, the resizing of buttons just by dragging a corner is pretty cool.