possible cold joints

hello all. I replaced a stop valve the other day that the previous homeowner had installed about 7 years ago. The old valve came right off once the bead of solder around the joint melted. There wasn't any solder in the joint. It wasn't leaking. I replaced it for cosmetic reasons. This has me worried now because I know they also did some pipe work in one bath behind a tiled wall. I'm trying to weigh my options as far as ripping everything out or just keep an eye on it. I was told by a retired plumber that he had removed cold joints that were 20 years old and never leaked so if nothing has leaked by now don't worry about it. I'm still concerned though. Any ideas? thanks

I've seen a lot of them myself....probably had the heat right at the point where the copper came out of the stop...the thinner copper heats more readily than the thicker brass....solder melts around the copper but doesnt flow into the valve socket

probably not a problem in the wall...thats most likely copper to copper......

Thanks. Your probably right but I couldn't resist from going underneath the bathroom vanity where the other pipe work was done and taking off a section of drywall. The joints aren't the prettiest but they're not leaking. That's all I care about. The only thing I didn't like was the cold water supply pipe that comes off the elbow to the stop valve is resting on the drain pipe. Basically the drain pipe is supporting it.