Bought a used carbon bike:
This is on the outer side of the clamp area for the seat post. I checked the inner side (by taking the seat post out) and didn’t see any delamination. I can feel the crack with my fingernail, the coin tap test is inconclusive for me since the area has difference in wall thickness.
The hairline is quite symmetrical. I assume the clamp was always mounted with the correct amount of torque.
What do you think?