I have been concerned because the receipt notice that my wife received was not very legible.
What I mean is that it looked like it was printed from a printer that was low on toner and is extremely light. Will USCIS issue another letter if requested and can I do this by mail? I was hoping I would not have to request an infopass appointment just to get a decent looking notice.

Now that is a new problem. Is there any way you can get it photocopied on a high contrast setting so that you have a legible copy? That might be a lot easier than trying to get it redone from USCIS - I think they would probably charge you for the new copy and they don't use Kinko prices.