I would strongly recommend you get it fixed NOW before it does much more damage to the guitar. There's no way it can be a finish crack only - think about it. Why would there be particular stress on the finish only, in a place which just happens to be exactly the same location as a joint between two pieces of wood, unless the two pieces of wood had moved relative to each other? That tells you there has been movement between the pieces of wood, so even if your magnified view doesn't show it to you, you have a direct piece of evidence which tells you that the joint there has moved. Since glue sets and then shouldn't move, you know there is a crack there of some kind.
If a luthier can find a way to inject glue into the crack (maybe even drill a tiny pilot hole to get a needle in there) then you can clamp it up, let it set for a couple of days and it's fixed with no further damage. Otherwise you are waiting for a crack, which you KNOW exists, to open up without warning and do an unknown amount of damage to the surrounding structure of the guitar. You really shouldn't give yourself a false sense of security about it.