Where exactly did you touch it? Was it back near the cowling and possibly still warm from flight?
To be fair, both places you touch should have the same angle to the sun. Red on the side couldn' be compared to gray on top. And, they should have the same heat transfer paths too. For instance, if the gray was backed by foam and the red was just layers of glass forming an air scoop, then that would not be a fair comparison.
Cozy Mk IV #1334