I checked all the tank stuff repeatedly
... what makes me sure he got out is that Slithers keeps climbing up onto the background and has only been doing this since Squiggles' Houdini act .... it's as if Slithers is looking for Squiggles .... and the scent trail ends where Squiggles squeezed out next to the thermostat cable (which has since been tightened) .... I'm running off to get more bottles for bottle traps today ... still crossing my fingers ... thanks for all the suppurt guys.