Why does my Playbook wifi setting save the incorrect password?

I have a relatively small house here in Arkansas, with a decent router and a wifi extender at the other end of house. No problems to connect a desktop and laptop computer with wifi, as well as 2 Roku units and my wife's Android tablet. My Playbook connects with a good signal, but when I need to re-connect (for whatever reason) by signing into Saved Networks, I need to clear out the saved password and re-enter the correct one---then it will connect right away. For some reason, the password that's saved (can't tell what the characters are because they're asterisks, of course) is only 10 characters long, and my actual password is 15 characters long. I've tried a reboot numerous times, tried deleting my Saved Networks (my home router is the only one saved) and saving it again. But no matter what I seem to do, it always has 10 characters saved. Clearing the password box and re-entering the correct one solves the problem---but I'd sure like to know what is causing this. Any suggestions? Thanks.