It depends when you bought yours. Dell somewhat changed the construction of their monitor line starting with the 30". They changed from that oval base to the triangular one (among other things, but that's the easiest way to tell). I don't know if this changed the height, though. It may have.

Congrats on the monitor! I love my Dell, and I recommend their monitors exclusively. I fear the day when they have to start figuring out how to make increasingly higher profits on them, causing that Dell line to also go down the toilet.