fire place restrictor elbow gas leak

[plumben]

Any one ever seen a restrictor elbow cap become loose and start to leak, went to a job today where we fitted a fire 6-8 months ago and all of a sudden there was a smell of gas, that turned out to be the cap on the restrictor elbow, yet it'd been fine for 6-8 months, I think someone had been fiddling personally

 

[woodsy]

Would suggest it's likely to have been fiddled with, only had them leak on top screw after years when washer has perished after numerous removal and replacement.