I would get a small rod (something like the refill out of a ball point pen if it will fit in the hole) and measure the depth of the holes in your inserts.
The new 2009 footstrap screws (for use with thicker anti-twist plates) are supposed to be 32 mm long.
The previous years (1998-2008) footstrap screws were 28 mm long.
If you measure the depth of the hole in your new board, and it's at least 30 mm deep, then with the thickness of the footstrap webbing and the oval toothed washer, you would be OK to use the new 32 mm footstrap screws.
If the hole is shallower (say 28 mm) I would either cut/grind the anti-twists to sit side by side, or add a washer or 2 on top of the oval toothed washer.
Did any oval toothed washers even come with your board?
Did you measure all of your footstrap screws to ensure that they are all 32 mm long?
If it concerns you too much, perhaps a stop at your nearest Starboard dealer to purchase 4 of the older 28 mm long FS screws would be a good idea.
I will bring this up with Tiesda and see if this is one of those "Gosh...we didn't think this through for the Evil Twin back footstrap" deals.
Thanks for the heads up!
P.S. Remember to rub a bar of soap on your footstrap screws before you install them for the first time. The soap serves as a lubricant and will allow the screws to cut really goos strong threads and also allow you to tighten them more securely.
Put them in, and after your first session on the Evil Twin, retighten them and that should take care of any foostrap issues for the life of your board.