The most common false alarms we've seen are for sites that are very slow to load. Our daemons only allow 20 seconds for a site to respond, so if your site can take that long to load from a very remote location, this is almost always the reason.

Some services are also behind firewalls that throttle connections coming from the same IP addresses over and over again - which is exactly what our uptime monitoring feature does. If you are using a big web host such as GoDaddy, ask their support department about this. If you are hosting your site on your own server, make sure to white list our monitoring IP addresses, which are listed in the Uptime -> Setup page in your analytics reports.