ITA!
I think any position where your baby's chin is tucked can cause problems. I know that for preemies, they may do a "carseat test" before allowing you to leave the hospital(where they put baby in the carseat, all strapped in, and monitor the O2 for an hour). They do this cause small baby's sometimes slump over too much in the infant carseats, and that can be dangerous on the way home...especially if you do not know!
IMO, this is really only an issue when using the cradle carry with smaller babies and/or deep pouchy type slings.