A.B.
My 4 1/2 month old daughter has been doing the same thing since we started putting her in the crib (and that includes sleeping through the night). Not only does she spin around, kicking the covers off along the way, but she loves to feel the soft bumper against her head. No matter how many times I get up and put her back in the middle, she still ends up spinning around and leaning against the bumper. I know there are some that frown upon bumpers at all, but I'd rather have her feel something soft against her head than the hard rails. Besides, at least her arms and legs can't get stuck with the bumper there. Suffice to say, if she's sleeping and that's what makes her happy, I'd let her go. No harm, no foul. :-)
Good luck and enjoy!