I have noticed this exact bug with the carpet; but it only ever happens rarely. The intended behaviour of these placeables is for them to be oriented perpendicular to your character's facing, always. I just tried it in the Vistani Camp area for example; on the first, third, fourth and fifth attempts it was placed correctly. The second attempt, it randomly rotated it 30-50 degrees to one side.
My assumption is that this is a bug being encountered by all similar placeables and that whatever variable determines the perpendicular facing is going awry.