Granules in a gutter deserve context. Their presence alone does not establish the age or remaining life of a shingle roof. The roof surface, recent work, weather history, and pattern of material loss need to be considered together.
What to do next
Photograph the observation from a safe location and request an assessment if the condition is changing or accompanied by damage. Ask the roofer to document the shingles themselves. Avoid deciding on replacement from gutter debris without inspecting the covering.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.