Someone here mentioned it might have something to do with the DDOS protection strengthening we did a few day ago. I'll contact Wil and see what we can do to make it work.
It makes sense if a single endpoint (or a small number of IPs) coming from MrWil's service is constantly hitting your api URL. I'd imagine that X number of people using it * 1 or 5 min intervals is going to amount to a fair bit of traffic and trigger some kind of anti-DDOS response.