Ok, I think I got it. You can replicate the problem by doing the following, at least on the Mac version at 1280x800:
- Go to store
- Open up the description of a purchase option by pressing the ? button
- Try to buy but don't have enough gold for it
- Use the back button to go to main menu
Now when you return to the store or the deck builder, you'll see that the texts have been offset to the left.