Alan Ratcliffe wrote
Gibson style guitars have a bit of a weak point at the point where the headstock meets the neck. I've seen headstocks snap off there from guys bumping the endpin a bit hard when they put them down (that's right, bump the bottom and the top breaks!). Cracks from temp changes are also common, as is shock damage - even while in the case. This is why many manufacturer's who have a similar angled headstock either put a volute at the top or scarf joint the neck.
This I'm familiar with, which is why I'm very very careful with my LP as well. Shock damage is a possibility as it came from out of town via a courier service. In my hands they get treated carefully whether in the case or out.
Make sure that your case is supporting the guitar properly along it's whole length. With some, the guitar is only supported at the end and at the neck rest, which makes it more likely to be damaged if you knock the case. I like to keep a bundled up cloth beneath the headstock too.
Its in the original Epiphone hard case which seems to be ok, but thanks for this tip - I'll take another look and add a cloth to it.
You need to make sure it's just a finish crack. Loosen the strings, hold the neck near the top and push the headstock back and see if the crack opens up. If it's OK, it's safe to leave. If it does open up, take it in for a repair. At this early stage it's an easy repair (glue injection) that will leave the neck stronger and be virtually invisible.
I'll do this test tomorrow when I'm more awake (just got in from practice) and there's better light. Either way it may well be a good time to get the nut replaced with a decent one at the same time. Thanks Alan.