You gave them a tech analysis that should be worth some money, for free, at the same time (hopefully) bringing to their attention how bounty programs are a helpful thing for everyone. They should be feeling very lucky about it.
However, the thing that worries me with these things is that, what if some "bad guys" already knew about this and exploiting it and now that the bank is aware and might close the hole, makes them angry and looking for retaliation?
Hopefully you are taking precautions to be anonymous, but I know that where I live if I were to pull a stunt like that I would seriously consider watching my back for a while.
Sad world we live in :( so take care OP.