Yeah, this one's common and yes, it's a safety issue. The chain should be stationary at idle. This usually means the idle speed is set too high.
The fix is to adjust the idle screw on the carburetor. You'll need a small screwdriver. With the engine off and cool, locate the carburetor adjustment screws. The one marked 'T' or 'LA' controls idle speed. Start the saw and let it warm up. Then, with the chain brake off, turn the idle screw counter-clockwise in small increments until the chain stops moving. The engine should still run smoothly without stalling.
If that didn't work, the clutch might be worn or sticking. The clutch engages the chain at higher RPMs. If it's worn or gummed up with sawdust, it can drag at lower speeds. That's a more involved repair.
Heads up: Never run the saw with a moving chain at idle. Always engage the chain brake when you're not actively cutting, especially if this problem occurs.