Just chiming in that I've never had this experience with them. I set, hit, and depend on those limits regularly. I would be wildly interested in reading what their support analysis had to say about this situation, if such a postmortem was done.
So far it was just "investigating". From the logs, my best guess is they sent all the requests at approximately the same time, and whatever limiting they do doesn't react fast enough.
I get it, the API key was my responsibility, but, setting the dollar limit is exactly the guard they suggest against that.
