Just noticed this as well. There is a spot for a password if you go to Account > SMTP > Gmail SMTP. It's grayed out in my settings so I couldn't change it even if I wanted to. What are you using for a Gmail password setting? I'm using 2 step.
Unfortunately it looks like deleting and readding is the only option....but it should be easier than that.
Here's a link that may help https://support.google.com/accounts/answer/6009563?hl=en
On that web page scroll down to "Still having trouble signing in" and follow the instructions. If that fails, deleting and then adding the account back may be your only solution.