Baby boy keeps his head tilted to the side sometimes

A quick question.. My son is 11 months old and for the past few days he's suddenly tilting his head every now and then. It's only for a few seconds but I find it so strange! I've tried to figure out when he does it (like when he's tired, for example), but there doesn't seem to be any pattern. Otherwise, he's perfectly healthy and doing great! Does this sound familiar to anyone??