i got an acceptance from a school that gave me 2 weeks to decide and with no offer of financial assistance. i emailed the director of the AuD program to ask them if they offered financial assistance, and she responded back offering me an assistantship through email. i don't know if i still would have been offered it if i hadn't asked. remember that schools are trying to fill a certain number of seats, and if they accepted you, they want you to attend. they know they have to be competitive, and universities everywhere are trying to increase enrollment.
also like many people have said, departments may not know if they have the money to give to students. the year i applied to gallaudet, they didn't find out if they were going to get the federal grant until may. so i had to make a decision that was a gamble.