I noticed it on the home network when I tested it this week. So for a lark I brought it in to work today to test it on the network there. It should have had a password for that network, and didn't. I connected, typed the password, browsed a few minutes, then powered off. turned it on about 10 minutes later, no saved password, didn't even recognize the network as the one I usually join with.
Then, checked it at our local coffee shop. They change the password about every 2 weeks. Doubt it would have had the current password in it already, since I rarely connect to wifi. It didn't, went through the same thing.
So, it's neither remembering networks its connected to, nor is it remembering passwords after it powers off. that seems to be the key. tomorrow i'll check if it can remember the password after just going into sleep mode.
but, since i don't use the kobo store from the ereader (it's never managed to store my country data and card data, which i had assumed was because i travel between 3 countries regularly), i can't easily buy books from it anyway. so i only ever use wifi for sync, which isn't a common occurance. so a factory reset to fix something that's a quirk rather than an annoyance seems a waste of my time.
and who knows if the next upgrade won't restore my wifi and change something else?