It is not a good idea to have any strain on the piping or gas valve.
That can cause a leak. It can also cause the thermostatic automatic
valve on the water heater to malfunction, which could just be a
nuisance or could actually be dangerous. Pipe strain also violates
code. See Section 407.2 of the International Fuel Gas Code. It is
not a good idea to use real soap and water to test for leaks. Soap is
corrosive to the piping over the long haul. If you did use soap, wash
off the joints with plain water. We use stuff that is non-corrosive.
The pipes should all be square, level and plumb. Diagonal piping is
often frowned on by local gas companies. In addition, I hope your
uncle installed a drip leg (sediment trap) on the gas line where it
connects to the water heater, as it protects the gas valve from dirt
and scale. It is also required by code (Section 408.4 of the
International Fuel Gas Code).

Stretch