no country for old men - Was Chigurh in the hotel room when Sheriff Ed Tom entered?

He's in the room next door.

If you watch the scene again, Tommy Lee Jones notices the lock is destroyed and then proceeds to clear the room. The scene then cuts to Chigurh in another room of the motel listening to the sheriff and watching his movements as shadows through the destroyed lock of the door leading to the adjoining room.

Reference:
http://www.youtube.com/watch?v=fcjRNOfvVgM