Is this normal?

Daniel absolutely loves eating paper. I just don't get it--we have all these great toys and chewy plastic devices and all he wants to do is gum paper until it turns into a mushy mess. I carry him to the mailbox every day (to get the mail, not to send him away--that came out all wrong) and he usually gets upset if I don't let him put the mail directly into his mouth, straight from the mailbox. I figure some of it might be important, so I sort everything out when we get back in the house, then I give him the junk mail to chew on for awhile. Funny buddy!

Cardboard is equally delicious: