Bank Custodial Account - Just Turned 18?

So I turned 18 about two months ago, and my mother opened a custodial account for me at TCF Bank (we live in Michigan). I tried to withdraw $80 today, and the teller refused and said that I needed my mother present to officially turn the account over to me in order for me to use it. I was researching online and a lot of websites say that the second I turn 18, I can prove my identity to the bank and the account is automatically turned over to me (without a present guardian). I withdrew $200 from the account with no difficulty about a month ago, and I am really confused as to what my rights to the account really are. Thank you in advance for your answer!