Regulator or cylinder issue ?

[Henryevra]

Hey everyone. A newbie here. I had a question regarding my Oxygen Regulator single stage, click type with adjustable flowmeter) and Nitrogen Cylinder.

I have turned the cylinder's supply off, yet my regulator seems to show a pressure reading after a couple of hours.
And when I turn on the regulator, nitrogen flows and the reading goes to nil fast.

Should i be worried about a leak or the cylinder not being screwed off properly ?