BMW gas lines have a habit of "Sweating" gas when first pressurized cold and then not showing any signs of leaking for a while longer.
The V12 has 4 gas lines on top of the engine and 2 behind it that need to be changed about every 100,000 miles or 10 years which ever comes first. A significant number of 850 owners experienced fires on top of or behind the engine from "I can smell it but not find it" leaks. (That is about a $10,000 fire from a 6" hose)
Just replace all of the rubber gas lines in the engine compartment as insurance. Use new clamp too.