Copper supply line - solder loose?

Folks,
In my efforts to remove a toilet water supply tap, as soon as I put some purchase onto the retaining nut, the entire assembly moved a fraction, nut and tap body. What's got me worried is how often can this movement in fact be the copper pipe soldered joint moving around?
I did not proceed with the tap removal and I'm not seeing any water leaching through the sheet rock or under the baseboard, but I'm nervous as I don't know what is going on behind the wall. I'm going to buy a Dremel and grind off the chrome vanity ring around the pipe and then see if I can push a zip tie or wood skewer into the wall where the pipe is and see if there is any water or moisture on the zip tie or skewer.

 

Stuff a paper towel into the whole and see if it's wet. Is it in fact soldered on or is it a compression fitting? If you have any doubts remove the valve and go with a shark-bite valve. No soldering or compression. Just snap it on.

PS...Send u s Pic

 

I really doubt if you twisted or damaged any copper.
Compression fittings like your valve are often not on very tight.
When you tried to remove the nut, the valve turned slightly on the pipe. That should be OK if the nut is not leaking.
Use two wrenches to loosen the nut, one to hold the valve and one to turn the nut.

 

Thanks all. I did have a wrench on the tap body braced against the floor. Thing was I had it on a towel which may have given enough or perhaps there was slight play in the wrench I had on the tap body. When I put some purchase onto the nut the nut didn't turn but something (hopefully the entire tap) moved a fraction. I thought oh no...and it's Saturday. I moved it back the fraction. The tap itself is fine. no leaks there. I was changing it out as I'd deluded myself into thinking that the new toilet needed the flex connector and the old style metal crimped feed from the tap into the fill valve would not work. Well the fill valve in the new Kholer is a Fluidmaster and that was what was on the old toilet. So I didn't need to touch the supply tap at all.
I'll still get the Dremel, but I feel a bit better. I wouldn't think the soldered joints would break loose, but water, plumbing……hmmm.
Thanks

 

If you dont know for a fact that it's a compression fitting on a copper pipe, its possible that it could be an npt fitting on a nipple, and the whole thing is turning out.

 

I think it is a compression fitting, in that I had to replace the one upstairs and that had the compression ferrule on the pipe. They both look like the original taps, the outlet from the tap is a metal spiral that is crimped onto the tap body rather than the flex braided connector.
Thanks