One of my own babies REALLY liked lying with her head off to one side, all through the last several weeks of pregnancy. It hurt, actually--pinching my tissues between her head and my pelvis on that side (she was big). I would massage there, and push on her head until she moved it. It didn't even occur to me that this would cause a positional issue at birth (I was UP/UC, no mw to talk to and being a mw didn't seem to do me any good at the time!). In any event, she tucked her chin and dived in properly, once labor started (or before, I'm not sure), and came out in perfect vertex position.
Soon after the birth, tho, first time she was laid down on the bed on her back--she turned her face to one side and tipped her occiput way back so it was nearly touching her shoulder, face looking upward--and reached up a hand and stuck her fingers in her mouth. I took one look and knew that was the position she'd been in, all those painful times! It was always her favorite sleeping position.
Not to worry! I've also seen this sort of thing several times w/my clients, especially those who've had at least one baby already. So far, the babies have all tucked into center before or during labor, and birthed just fine. They can find the way, and they usually want to come out!