A payment failed but my page is still taking orders. Should I do something?

Yes, but there is no emergency. Your card is retried automatically, you are emailed, and Settings → Plan & billing tells you exactly which state you are in and what happens next. That screen carries two buttons — pay now with the same card, or use a different one — and either clears it immediately. It stays reachable even if your page has stopped, deliberately: a restaurant that cannot open its billing page cannot pay.