I had a similar issue at my parents' place a year back—metal edging looked fine from a distance, but water was sneaking underneath. Ended up with some moldy insulation, total pain to sort out. Definitely worth double-checking the edges every now and then...
"metal edging looked fine from a distance, but water was sneaking underneath."
Yep, that's exactly why visual checks alone aren't enough. If you're inspecting your roof edging, here's what I'd recommend: first, gently lift or pry up sections of the metal edging every few feet (carefully, obviously) to see if there's moisture or discoloration underneath. Second, check the attic insulation directly below those spots—any dampness or moldy smell is a red flag. Did you notice if the water infiltration was worse in certain areas, like around corners or seams?
Had a similar issue last spring, turned out corners were the sneakiest spots for leaks... Did you find any rust or corrosion under there, or was it mostly just dampness?
Corners can be tricky, sure, but I've found seams along the straight edges can be even sneakier. Had a leak last year that looked corner-related at first, but turned out moisture was traveling along the seam... worth double-checking those areas too.
Good point about seams—I had a similar issue last spring. Thought it was the flashing at first, but turned out water was sneaking under the metal edging itself. Did you end up sealing yours, or replace the whole strip? Curious what's most cost-effective.