First: Orion Nebula for the win!
Second: as it happens, I charged my Glo today. And it eventually showed the battery with the + sign of its own accord, and, when unplugged, tapping on the battery gave a reading of 100%.
So, no, I'd say it's not normal.
Are you charging via a USB connection to a computer, to a USB hub, or to a charger device plugged into the wall? If the second, is it a powered USB hub? If the third, what sort of charger are you using? (My suspicion is that perhaps the Kobo isn't getting quite enough juice to charge properly.)
All best wishes.
Rob