2004 D Iowa State Quarter Varieties

I went through a bag of 100 Iowa State Quarters last night and saw a number of in lettering differences printed on the coins. Often, "QUARTER DOLLAR" or "E PLURIBUS UNUM" were printed with round looking font and often with a flattish font. I wonder if this is because of different dies used at the mint?

The biggest difference in font I found was on "UNITED STATES OF AMERICA" where one coin - only one - out of the mint bag of 100 coins was very different than the rest. The lettering was much flatter and wider than most coins, as you can see in the pictures below. This put me in mind of the bicentennial dollars that had Variety 1 and 2 listed in the Red Book showing differences like these quarters have. I'm wondering, are these varieties due to dies used, or is there something in the minting process that results in this kind of thing?

Thanks in advance.