Google apparently paused the rolling out of Android 4.0 Ice Cream Sandwich to Samsung Nexus S devices in some regions while it monitors the feedback from users.
According to TechCrunch, some users encountered problems after updating their Nexus S devices such as battery drain and poor wireless signals. Google Community Manager Paul Wilcox posted a reply on Google Mobile Help Forum reassuring users that the Android 4.0 update will come eventually.
Google Community Manager 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."
While Google has not revealed the exact reason for the delay, it is possible that software bugs are causing the problems. Apple and Nokia also scrambled to provide bug fixes for the iPhone 4S and Lumia 800 respectively after users reported battery woes on their phones.