Hot Water faucet groaning

Just had the check valve replaced about a month ago.

If it's an aftermarket faucet, note that some of them come with check valves. Like the $80 kitchen faucet I bought at Walmart. Didn't notice that it wouldn't drain out properly when I winterized and the water left in it froze and broke a pipe on the faucet and caused the house plumbing to burst open too.

So, if it's an aftermarket faucet, check it for a bad check valve at the connection to the house plumbing, and remove them if you winterize. They're not needed in a small RV.

All of them? OR just one faucet?

All of them..then hot water heater check valve in outlet fitting on tank
Replace with a brass one (as suggested) vs the cheapo plastic junk OEM one.

Only one faucet...then disassemble faucet replace 'cartridge'

Sounds like the check valve on the back side of the water heater is vibrating due to a weak spring.
Have encountered this 2x and in both cases a new BRASS valve fixed it.
Good luck and let us know the result.