OK, I have a weird question about postage stamps. For those of you who didn't know, the price of US stamps is going up to 39 cents in a few days. So I just bought a book of stamps, and they were sold to me at the 39 cent per stamp rate. However, they just say first class... no numerical value on them. I need to mail a letter to Canada, which is 60 cents, and I was just going to put 2 stamps on it. The question is, can I still do that even though the stamps don't actually say "39 cents" on them? Is that automatically implied?