@Dave....
After a 30-mile ride today, I tried your 2 ideas, letting the bike idle in the driveway for about 30 seconds, then lightly cracking the throttle as I turned the key off. Nothing for a couple seconds, then a quiet "belch" out the exhaust.
I've decided to view it as a Charming Idiosyncrasy.
Mind you, the bike is still in break-in, is box stock, & it was about 40° out.