From hostgator two days ago:

Over the next few weeks, we will be making network upgrades which may potentially impact your hosting service.

These upgrades are designed to improve overall network reliability, and we believe you'll be pleased with the results. However, the process may cause up to 5 minutes of degraded connectivity, or possibly even inaccessibility, to your hosting server. The server itself will not be touched as part of this maintenance.

Your satisfaction is our top priority and we appreciate your understanding during this scheduled upgrade.