Just got off the phone with the IRS and figured I'd post what I found out here, as it may affect others as well.
When I filed my taxes, I used TurboTax online, had my refund direct deposited in my account, and had the preparation fees deducted from my refund (I think this is the key piece to the puzzle). The way this is processed is that your refund is direct deposited to a 3rd party bank (Santa Barbara Bank and Trust), where the fees are deducted and the remainder of the refund amount is then transferred to your personal account. When I spoke to the IRS about the stimulus check, I was advised that because my tax refund was direct deposited into a third party account rather than my personal account, they will not be direct depositing my stimulus check. They said that because the original deposit account was not my personal account, I will be receiving a paper check in the mail, to be mailed by June 2nd...
Anyway, just wanted to share this info in case there are others who filed the way I did and would be wondering why you hadn't received your direct deposit yet...