OCD?

For several months now, we have seen Sam go to bed in exactly the same fashion pretty much every night. He puts his Lightning McQueen pillow in its position, he puts his sippy cup, with the spout towards him in the corner by the pillow, then he puts his green blanket along side of where he will lay and then lays down and we cover him up with his Cars blanket. His pillow, (as if he can read the word 'speed' on the top) is always put in the direction that he sleeps... along his headboard. He doesn't seem to notice or care that he can hardly squeeze in there anymore. His legs either hang over the side or he crunches them up on top of him. It looks extremely uncomfortable... cozy, but uncomfortable. And another thing he does is that he must crawl into bed on the same side every night. Then he asks me to sing a song. I ask him which one. He says, 'Sunbeam' and we sing it.
Another oddity of his is often when he gets out of his bath, we go to his room to put on his diaper, and he wants to lay out his towel so that he can lay on top of it. But it has to be laid out perfectly. All the corners have to be laid out just right, and there can't be any wrinkles. Only then will he willingly lay in front of me so I can put his diaper on.

Is this just a routine? Do most kids have specific quirks about certain things? Or does Sam just have a small case of OCD?

So my question is... what does your kid do the same every time it is done?