The N54/N55 engine(s) make so much tq down low its really hard to lug it. Even when I go around a traffic circle(or driving slowly in a residential area) in 2nd or 3rd(1,100rpms)... the engine just picks up speed with no issues.
I think if you were to do that in 4th or 5th gears.... or anytime you get the engine to shake/lug,,, that would be bad. But as long as the engine isn't protesting/shaking... I think that is ok.
Now when doing that I would not go WOT at those low revs... I would not want to squash my crank bearings... but for light acceleration I see no problem driving like that.
Normally when the engine revs fall bellow 2K rpms... I grab the next lower gear.