Yes, it's dangerous. The chain should be stationary at idle. The cause is an improperly adjusted idle speed.
- First action: Let the engine warm up for a few minutes.
- Locate the idle speed screw (often marked 'T' or 'LA' on the carburetor).
- With the chain brake disengaged, turn the idle speed screw counterclockwise in small increments until the chain stops moving. The engine should still run smoothly.
IF THAT DIDN'T WORK: The carburetor's low-speed (L) jet may be set too rich, or the clutch springs could be worn, causing the clutch to engage at too low an RPM. Adjusting the L jet requires specific knowledge. If the chain still creeps after adjusting idle speed correctly, the clutch assembly likely needs inspection.
HEADS UP: Always ensure the chain is stationary at idle before beginning any cut. A moving chain at idle is a major kickback risk. If you're not comfortable adjusting the carburetor, take it to a service technician.