[SOLVED] css ata question: should be simple... my does my submit button resize?

(By the way: I think there should be a CSS and Styling subforum here...)

If you go to my blog, on any post, and look at the "Post Comment" button below the comment area, such as here: http://www.derekbeck.com/1775/info/noble-train-2/
you'll see, even as you mouseover the button, that the size does not change.

Yet, on this contact form: http://www.derekbeck.com/1775/contact/
the "Send Email" button, which should be styled the same as the above button, has a strange behavior as you mouseover the button: it grows a few pixels wider.

I've studied the CSS and I cannot figure it out. Anyone else with fresh eyes perhaps have a clue what I'm missing?

Thanks! Derek