Tub spout supply pipe question

I was wondering if you guys think this sounds OK....

I replaced a bathtub spout. The old one connected to the 1/2" pipe with a plastic adapter. Thinking that the pipe was sodered behind the wall I only used one wrench when trying to remove the adapter. To my suprise it turned the copper pipe not the adapter. I then used two wrenches to remove the adapter and then retighted the copper pipe a bit before installing new spout.

Is it typical for that connection of the pipe that holds the spigot to be threaded?

Fearing that I caused a leak at that connection, I let the tub run for a long time and went down into the crawl space to see if I could see anything leaking from the crevice the tub pipes are in and I didnt see anything leaking down.

Is it safe to assume there is no leak then or do I have to open the wall to assure I didnt damage that connection?

In some cases yes, It sounds like what you unscrewed was a brass nipple which is a piece of pipe threaded at both ends connecting from the pipe in the wall to the tub spout.

I would redo the connection wrapping it with teflon tape with teflon dope applied over it and put on the new spout.
If the length of the nipple isn't correct for the new spout, then new ones are available in 1/2" increments.

DOes the new spout have a diverter on it for a shower? Did you activate that? The tub spout has a big opening, so it might not leak when filling the tub, but is more likely to if you are taking a shower since the pipe is then pressurized (since it can't come out that big end, it is forced up to the shower.

Loosening a threaded connection might compromise the seal, espeically if it was pipe dope rather than tape. Did it get tight? You might be fine, but tight with old, dry pipe dope, may not reseal.