perhaps he felt that he could not say the whole sentence, "mommy, can you please read me a book?" try letting him use simple words first, and then ask him, "How do you ask?"
I subscribe to the notion of laying down the law with the kids, and not giving in to their crying. however, I also agree that they should be rewarded for using their words (instead of crying). additionally, reading books each night is more important than discplinary skills...