I'd recommend running the sharpie test anyway to have a full edge assessment and see how severe the warp is. It may well affect more of the edge beyond what is visible. When you hold the razor on the stone, are you applying pressure? On some full or extra hollow straights, pressure can cause the edge to distort slightly and raise up from the hone as a result. It likely is a warp though, which is common on vintage razors. The rolling X is your friend in these cases.
Something else to consider: some hones aren't as flat when they're dry as when they've been soaked for a while. I read about that some time ago and I believe King hones were amongst the ones mentioned. I don't think the difference would be enough to visibly see part of the razor raising up from the hone, but it'd be worth a look. Hopefully someone with a bit more knowledge in that area will come along, since I'm nowhere near an expert on that subject.
Something else to consider: some hones aren't as flat when they're dry as when they've been soaked for a while. I read about that some time ago and I believe King hones were amongst the ones mentioned. I don't think the difference would be enough to visibly see part of the razor raising up from the hone, but it'd be worth a look. Hopefully someone with a bit more knowledge in that area will come along, since I'm nowhere near an expert on that subject.