Idling issue: RPMs slowly decrease until engine shuts off

[pattybags]

What do you guys think about this?
 
After a cold start when I leave the engine idling, the RPMs slowly decrease until the engine cuts out.  
 
I read the instruction manual.  I know about the engine cut off after 20 minutes.  This happens after about a minute or two.  And it doesn't happen after the bike is warmed up.
 
Hmmm...

[pattybags]

Service guy recommended changing spark plugs. Checked the owners manual and I should have done that 1200 miles ago.
 
Anyways, I'll report back next week after the plugs are changed.