The check box says "Remember Login". There's 2 ways to interpret that, and I may have been making the wrong one. I take that to mean: "remember my userid". And since Chrome always fills in my userid and password, I have never checked that box.
The other way to interpret it is: "keep me logged in".
It seems to me that if the purpose is really to "keep me logged in" then that's what the checkbox should say. (A lot of websites do use that phrase.)
I turned it on, and we'll see if that's the issue. Thanks.