Good luck finding him (& in good condition). You'd be surprised at what snakes will squeeze thru to escape...I once had a hatchling king snake that escaped
thru the tiny gap in the track of the sliding screen lid (on a glass terrarium). I found her pretty fast...hiding in a boot in my closet. The sliding screen had a
peg that secured it, but even with the peg in place, there was just a little bit of wiggle room for that silly king snake to find her way out. From then on, I had
to tape it so it couldn't move, until I got another cage set up; and from then on, I've made my own cage tops. Hope your little guy turns up. Don't give up!