Leak in new copper lines

We just had the plumbing in our house completely redone with new copper (installed in our walls) due to leaks in the copper pipes under the slab. The plumber has finished the job, but the sheetrock installer has not yet finished the walls. Due to a misunderstanding, the plumber installed a new shower head, but I preferred the old, so over the weekend, my husband replaced the new shower head with the old one. A short time later, we noticed water dripping in the wall near the shower valve, along the new copper
joints.

My husband thinks he may be responsible because he replaced the shower head. If the walls had not still been open, we would not have noticed the leak. Is this correct?

Thanks to anyone for their opinions.

Greta

You need to determine exactly where the water is coming from before assigning blame. Use a flashlight and look for the highest point that there is a leak. Is the shower head spraying water back into the wall? If so, you need to wrap some teflon tape around the threads. Could also be the shower arm had loosened up when he changed the shower head.