Typically if you are disclosing the fee at account opening then there is no requirement to give additional notice before charging such a fee. This case is a bit different as the Bank may have created a sense that it doesn’t charge the fee. I don’t believe there is a regulatory requirement that would require you to give the 30 day notice, but by doing so it would be a good customer service move and would give you a pretty good argument about it not being a UDAAP issue.
In the regulatory environment that we are in know, I could see this potentially being spun into a UDAAP issue. I like where you are headed with the 30 day notice, and that does sound like the safest route to go.