Agree with the others here, this is normal behavior for a BP. They are "ambush-predators" meaning they prefer to lie in wait for clueless prey to walk by, then pounce!
What you're seeing is a clue that his thoughts are on food. BPs do not go in search of prey when hungry, unlike many other kinds of snakes do. They peek out of their
secure hiding place & wait. If they were humans, they'd be waiting at the front door for Domino's pizza to get delivered.