Sorry the site was offline for a short while - I kicked off a re-index of the site to pick up the HTTP -> HTTPS changeover and, well, I didn't put any rate limits in place so Google went full bore at it. Having the site hosted in Google's data centre probably helps it go faster than normal.
In other news, I now know the site can scale to handle an insane number of requests if it ever needs to (as long as I put some more coins in the meter).