When I used my totem in a normal room, my totem's planks show that they're customized but I didn't customize them before. When I put a plank (not part of the totem) it shows the default plank.. It was on a dual Shaman map and the other Shaman was a Souris.
Here's a screenshot of it:

The customized planks were definitely someone's. They were one of the mice who was the sync. The customization by the sync always reflects in the items in your totem even if the sync isn't you, so the planks appeared as customized ones.

It was a guest.. It would be really weird.. a guest getting 7000 cheese. Also I think he had the default plans so.. (Not sure about this)

You were the pink shaman and the guest was the blue shaman, right? This cannot happen without it.

I don't really remember.. But how could a souris get 7000 cheese? It's like they kept their account open for around 3 days if they're farming.. BTW it's now working fine for me.

Someone besides you/Souris was sync then (guests can't be sync, and iirc you need a certain amount of cheese gathered to be sync to prevent bootcamp hacking) Simple.