My third baby (now almost 8 months) did the same thing - I noticed right before his 2 month visit, like you. The doctor just told me to lay him down with the head the other direction and it would fix itself. But it didn't. I brought it up again at his 4 month visit because I started noticing that his head shape was "leaning"! to one side and he certainly favored his head is the "cocked" position. Again, he told me not worry about it. We moved, so I changed doctors and at his six month visit I insisted that the new doctor do more than tell me he would grow out of it. THe condition is called torticollis and the new doctor said he was most likely born with it (the physical therapist agreed). We started physical therapy when he was six months old once a week doing strengthing exercises and stretches. He will be 8 months on the 13th of Dec and still cannot sit up and just now learned to roll to his "weak" side. Your instinct is right. I wish I would have pushed more because he is over 2 months behind in his physcial development. Because of the toricollis they do not have a good center of balance (their head is crooked) and it effects rolling, sitting and standing. He will be fine, I just wish I would have pushed more at 2 or 4 months so he wouldn't have been so behind now. There is anything "wrong" with her, her tendons may be tight on one side and stretched out too far on the other side - I was told most likely because of his positioning in the womb the tendons developed in this position and need to be corrected to equal distribution on each side to correct the problem. Physcial therapy has made a "HUGE" difference, I have been very pleased with the results.