Just keep your ears open as much as possible. My sister has a crested that recently escaped and he found his way into a vase that had a dried leaf in the bottom of it. My mom was spending the night at her place and something woke her up crinkling around in the bottom of the vase...
stuff like that makes me feel a lot better. I just want to find him. The dumber of my two cats knows somethings wrong, i'm banking on the other kitty to find him tonight, he's a very good bug chaser, just a poor bug catcher.