Don't get too excited about a US release too soon: Azumanga Daioh wasn't originally published by Shogakukan; that was MediaWorks. The move is said not to be relating to any disagreements, as apparently MediaWorks declined the project before it was offered to Shogakukan. Which sounds like a bad business decision, but oh well.
* This use of the word “literally” is dedicated to John Martone. No, you don't want to know why.