It seems that Google has hit the pause button on its rollout of Android 4.0 to the Nexus S that began last Friday. Details are still sparse, but many users are claiming that they're still getting update notifications over the air — the only difference is that when the update process is complete, the phone simply boots back into Gingerbread, so it appears that Mountain View is able to trigger some sort of rollback from afar. The exact reason for the move is unclear, but the company says that it is "monitoring feedback" — to us, that reads as though they're looking for a pattern in problems that users are reporting.

Says Google's Paul Wilcox:

If you received an update notification a little while ago but the update isn't currently available for your phone, this is likely the result of Google pausing the update in your area while we monitor feedback. The Android 4.0 update is continuing to roll out around the world so your phone will receive another update notification when it's available again in your region.

We've reached out for comment and will update the story when we have more information.

Update: Though we don't have anything official from Google, we've heard from trusted sources that this "pausing" is par for the course with Android's standard over-the-air rollout process — upgrades are paused between batches on a regular basis to be sure everything is going smoothly. We don't have anything specific on when updates for the Nexus S will resume, but we're told that as of right now, everything is still proceeding within the "in the coming month" guidance that Google had given previously.