A worn pressure reducing valve can cause noise in your piping. The proper term is "water hunting", not "water hammer." It means the defective PRV is hunting to get the proper pressure set in the system. When the PRV is new, it does this smoothly. However, as it wears, it loses the ability to adjust .... maybe it even "chatters" ... causing vibrations in the pipes.
Call this an easrly warning sign that your PRV needs servicing or replacing. (Most people just replace it outright) If you know how to solder copper this is a DIY project which can save you a lot of $$$.