I found a small, hairline crack at the lowest weld on the aft side of both gear leg sockets after a few years of flying my RV-6. I watched the cracks for several years and they didn't spread. In spite of not being able to see how these defects could lead to a gear or mount failure, three years ago I pulled the mount away from the firewall far enough to run a weld bead over the cracks.....just because.
By next condition inspection a small crack had appeared at the edge of one of the new welds. I've decided this is something I can live with since this appears to be a compression failure where the mount is very unlikely to ever fail and I've never seen a crack grow to more than 1/2" long in this area. I will continue to monitor this situation but doubt I will ever feel the urge to repair it again.
At least until some sharp-eyed A&P sees it during a pre-buy someday.