We don't have a formal OD program - just ad-hoc.
If you don't have a formal OD program, are you approving/authorizing ATM and one-time POS transactions into overdraft when no funds are available (prior to posting to the account)? If not, there is nothing for the customer to opt into except a fee.
There is no UDAP issue to offer at a later date than last July. However, make sure that if you didn't offer an opt-in, you also did not charge for any ODs caused by ATM and one-time POS transactions. If your system declines POA and ATM transactions when funds are not available, the customer would be opting into a service you don't offer. The potential UDAP I can see would be to solicit an opt-in for a service you don't offer.