I had my bathroom refurbished about 5 years ago. All is well, except for
one new thing that started last night.

When I run the hot water, the pipes apparently start to shift in the wall.
This has not happened prior to last night. It is loud. It sounds like
the joists are being pried apart while the water gets hotter, and a very
loud drip while it is cooling down. When the water cools in the pipes, the
sounds stop.

Should I worry?

Thanks.