I think users have no security issue here. Maximum the amount paid to the user less will they have to pay as fees when they spend it So little bit delayed will have no issue. 13000 Satoshi x 7 Payments will amount to more than 70000 Satoshi of miner fees . Like for Payaza Pay Pal etc verification is must thing now
I've already enabled security features like ACL and withdrawal limit. This shouldn't happen again is future.
One more thing I think I forgot to tell you. Regenerate your API keys if you didn't do that yet.