Had same thing happen many years ago with a hatchling Cal king in a glass terrarium with a sliding screen top. The peg used to lock the lid in place left just enough
wiggle room for the lid to slide outwards by maybe 3/8", but it was enough for a tiny snake to find & wriggle thru to "freedom". I'm glad you found your KSB, and
I found my albino king hiding in a boot in my closet, but I've been making my own SECURE cage lids ever since.I've kept many colubrids over the years...you
really have to be careful when they start off so tiny...it's easy to underestimate their escape-skills.