The truss or rafter could have been installed higher than the others at construction, pushing the sheathing higher. I see it quite often.
If it was wrinkled underlayment, you would likely see other areas as well. Since it is in a straight line from ridge to eave, it suggests a framing issue.
However, now that I zoom in on the pic, it does look like the shingles are a little peaked at the drip edge, which could indicate a wrinkle. 
btw nice flashing on the front of that chimney
Just for clarity. Trusses are engineered systems built off-site. Rafters are traditional stick-built. The age of the home sometimes can help identify trusses or rafter because trusses are relatively modern. The cathedral ceiling does not indicate one or the other unless you could visually confirm.
yeah, charming flashing is another issue 
I see what you saying, thanks Brian
Those appear to be cast iron pipes so 50’s 60’s for age?
It was built in 1957
Curious, was this bump over the vaulted section? Was there any visible sheetrock cracking?
No, I haven’t seen any damage inside. Infrared didn’t show any anomalies either…
Since there is no attic access and we are only doing a visual inspection. Report what you see and recommend further evaluation.
Thanks, will do.
My curiosity always gets the best of me on these types of things. Looking up the history on Google Earth Pro can show if what is telegraphing through is a new or ongoing problem.
Its a cool trick, Jeff. I just tried it. The resolution is too low to see it.
Resolution varies by year. If you click on the counterclockwise clock, it will allow you to toggle the different years.
I agree and have seen that many times, too, like Daniel…poor workmanship it was, IMHO.
The only things I can think of is:
1: Truss uplift but that would be confirmed on the inner ceiling below that truss but the sheathing would be awfully thin to make the upper truss chord telegraphed through sheathing and composition shingles.
2: No H-Clips on sheathing might be another thought if the sheathing was not staggered.
3: Another thought, someone went into the attic and used lumber as a support to prop up a sagging damaged rafter.
Observation: Thin long raised section on the roof, that corresponds with a roof support member, rafter or truss, being telegraphed onto the composition shingles.
Recommendation: 1: A licensed general contractor construct an attic access and hatch. 2: Further evaluation by a licensed carpentry contractor or general contractor.
Act upon any recommendations offered.
Limitation: No access to the attic.
Just my 2 cents.
Pic of my new re-roof. Six areas were raised like the OP pic.
They got it completed in between heavy daily rains.
The tar paper was too wet when they laid the shingles.
The self sealing shingles all went down after heat/cold expansion/contraction.
At least on mine… … …
It’s a high truss…we call these framing inconsistencies…this truss is probably sitting on a parallel wall or not lined up good during construction. If you look at a roof good from a distance you can almost see every truss location.
On top of noting it and calling for further evaluation try to get the seller to commit to an installation date. Useful information for the buyer, CYA for you.
Perhaps the roof sheeting is butted on the same truss. It would be hard to cause the roof sheeting to buckle at the same spot if the sheeting were staggered. Call in the roofing expert.
