With good reason, older gas line seals and such can be broken when moved around and such. Not all mind you, doesn't happen most of the time, but enough to be leery of it. Many, i would say modern or recent, but that is subjective. Have a gas line that is flexible allowing for the movement and such. Those can be pulled in and out a bit to help with cleaning. Hard piped, i would just leave it in place and do the best you can.