Same thing happening to me for gmail. For me even after checking my email on GNex the mail seems to still be left unread (when I log on a desktop, the email shows unread status). Could this be the reason?
Why is everyone so sure that galaxy S3 on Verizon will be flawless? Before GNex was released, it did not have any problems. The issues a few had surfaced after release LOL... The same can happen with S3 when they release on verizon.. Just my 2c.