sipoolowner,

If you only hand tightened; not to worry. You could not have cracked the copper pipe unless it was extremely corroded from acid water or you had a lot of leverage from a pipe wrench. What likely happened was that you just torqued the faucet body and/or supply pipes enough for them to move in their support/attachment straps and make noise.
Because the spout is open discharge there is almost no back pressure to force a leak unless the spot has an end diverter for shower head.
It cannot leak if the faucet is shut off and a leak can not be differentiated from the spout discharge flow metering when the faucet is on. Besides it could take a slow drip a few hours to accumulate a one gallon increment on a water meter.
To be on the safe side, take off the spout, remove the used teflon tape, retape and install spout; if you didn't do this when you removed it to inspect it. If you can not get it to the correct position when at maximum hand tightening; insert a piece of wood stick or screwdriver handle into spout end to get more leverage to rotate to desired resting position. If you need to go nearly a full turn and it is getting to tight to reach the position needed, it may be better to take spout off, rewrap teflon thicker and park the spout with out doing the extra turn.

Thank you very much, biorat, for the detailed reply.

Yes, I only hand tightened and didn't use any wrench/wood/screwdriver. And I retaped the pipe before reattaching the spout. I didn't notice any corrosion outside the pipe except a small amount of greenish stuff in the threads.

The spout does have a diverter for the shower head and we use this shower about 2-3 times / week.

From what I gather, it is not likely (and difficult to tell) that I damaged the inside plumbing but I'll keep an eye on any signs of leak on the nearby wall/floor.

Thanks again.

Could you have cracked a tile?