I agree with you 100%. If you let it sit and bleed down you will be more likely to see smoke. I never had issue, but my break in was fast :-)
Might be that 10+ dyno pulls at 6400 rpm.....
If it goes longer then the 300 miles I would see the dealer. Even now I would make them aware and get it documented... If it goes away then great. It was break in and you seated some rings. I have seen a couple uTube vids where I saw smoke, and my friends Charger blew smoke for a couple hundred miles.