Looking over my early 1990s Raleigh Grand Prix. Had the bike since new, only about 15K miles on it. Noticed paint ripples roughly perpendicular to the tubes. The ripple runs halfway around the chain stay on the drivetrain side (facing inwards towards tire), and about a quarter of the way on the other chain stay.
Both ripples are about a half-inch or so back from where the chain stays meet the bottom bracket lug.
Beginning sign of fatigue?