A small visible tile defect can coexist with a larger concealed problem, but hidden damage should not be assumed without investigation. The roof surface, underlayment, and decking need separate condition assessments.
What to do next
Ask how concealed conditions will be documented once access is available. The contract should explain approval and pricing procedures for additional decking work. Photographs and a clear location record help you understand why a repair scope changes after opening the roof.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.