I mailed out my invites two days ago, and just realized I have an uneven amount of stamps left on the last book I used. Since each invite is 2 stamps (one for outer envelope, one for response card), I should always have an even number, which means that I missed putting a stamp on one person's response card. I have no clue who, and I feel absolutely terrible!! How can I make it right? Am I crazy? I was considering mailing a stamp to whoever it is, if I ever figure it out.