Yup, there's a three bug limit in a few places. There's a limit for showing the review dialogs (so they don't keep stacking up forever), and there's a limit on the server side. Once it sees three of any given bug, it tells people to stop sending that particular bug again for quite a while. This prevents occasional situations on one computer from causing huge spikes in reported bugs. So long as the problem is widespread, we'll see lots of reports from different computers.