It's not the door seals, it's definitely from above. On the passenger side there is a mark where it's run down the firewall (I painted the firewall and floor a few weeks back, so it's noticeable on the new paint). I can't trace it all the way because the air conditioning stuff is in the way.
On the drivers side it's almost nothing. I thought it just might have been some water soaking through from getting in and out with wet shoes on Monday, but it's just a bit too much for that.

So nobody reckons it's the joint in the engine bay near the tags? It just looks sus there with the cracked joint compound.