Smell in gas locker

IanH

I changed the gas regulator, change-over valve and both hoses to stainless steel a while ago.

Since then I can smell something whenever I open the locker door. Of course it may have been there before and I didn't notice it, until there was a possibility that I'd done something wrong.

It's a sort of gas / musty smell but not as strong as gas.

I got our service engineer to check the installation and to carry out a gas-tight check and he says everything is fine.

Any suggestions?