On the up side it's always nice when thing are easy to take apart.
Oh yeah 2 out of 4 solder joists were like that real easy working with a toilet in your way, lucky im a thin guy and fairly limbal but that was to much! I had cramps to no end getting in there and replacing the shower body let alone the getting any pipe cutter in there as the pipes were up against the 2x4s grrrrr lol
I guess that is technically a case where the solder did not "wet" the joint.
How long did that joint hold up against the 40 to 80 PSI water pressure, water hammer, chemical attack by what's in the water, etc., etc.?
Is the house on well water?
Did you open the joint by twisting?