Yesterday I did a job at a duplex rental house. The landlord, who I know, helped me the whole time

I replaced 1 tub & shower faucet,2 lav faucets, fixed a couple toilets, and put some new ball valves in, and replaced water heater in basement. Everything went great.
Today I get a call from landlord, telling me that he is over there, & there is water dripping out of ceiling on top of heater.

He says it is coming from hot water pipe going to 2nd floor bathroom, & it looks like it is located somewhere between 1st & 2nd floor

And of course he wants to blame me since I did all this work there yesterday. Says I must have moved a pipe to hard or something, causing a joint to come loose in wall above. Its all copper.
So I have to screw up my day, & go over there, thinking I did something, unknowingly, to cause this.
I get there, & sure enough, water dripping down vertical hot water pipe, going up through floor, above heater. I do some measuring, & find out where pipes go up to 2nd floor through 1st floor kitchen. I look down & there is newer baseboard molding installed. I pull the baseboard molding off, & sure enough a nail is going right through the hot water pipe in wall.
Funny thing is, the baseboard molding was put up almost a year ago. Only thing I can speculate is that it broke the rust off the nail inside pipe, when I turned the water off, & back on yesterday.

Well at least it turned into a $$$ job.
