Hello!
This has happened three or four times now, quite unregurarly though, don't know what exactly triggers it.
I'm visiting Warlord and I have corruption. I walk to the quarantine array machine that cleans me from the corruption. After this I'll walk around revealing the right side of the map and notice that after 20-30 turns all the corruption comes back!
The first attached screenshot shows this happening in the log. I did check that my corruption went to 0% and it wasn't just some other robot getting scanned or something.
The next screenshot shows another game where I have 0% corruption and the second screenshot after 20 or so turns where I suddenly get 1%.