Flat spot on head

Anyone else have a little one that has or head a flat spot/side of their head? Our baby is 7mo and favors one side to sleep, so the one side of their head is flat behind the ear. Pediatrician says it will round out on its own now that they are sitting up more. Anyone else “wait it out” and have the baby’s head round out well? I’m getting nervous that it won’t get better.