are you and your wife using IMAP? this may not fix your issue, but i had this happen to me a while back. I fixed it by simply removing my Gmail account and re-entering it. its only happened to me once. see if that works for you.
I have run into this where my email notifications stopped working when I installed the LED notification patch. As soon as I unistalled the patch, they started working again. Just have gotten used to removing it and then installing it and turning off the LED before an upgrade. Not sure if it is related to your issue or not, but worth a try.
Sanyo SCP 4500 > Samsung SCH 1900 > Sanyo SCP 5000 > Treo 755p > Palm Pre > HTC Evo
I stopped getting gmail notifications today but when i browsed the precentral forums and found this thread it helped. i did what u guys said to do. i removed the acct and added it back but at first it didnt work so i left it alone for a few minutes and tried again and it worked. Thanks precentral boys