I don't see what's weird about Pandora deciding to remember Justin in her next incarnation, when clearly she has decided to remember enough about the shop that Hope decided to join the card tournament and had a list of cards ready. All knowledge about the card game must have been things that Pandora decided she needed to remember, too, for whatever reason. It honestly would be odd, then, that she decided she could forget about Justin when he's the shopkeeper and tournament judge.
And yeah, based on the font change in the third panel here, it's definitely something that Pandora planned for some scheme; not just a bit of whimsy because Hope is now a nerdy child.