I stand corrected on authorship, but I still think it was included by Spider Robinson in his memorial anthology for/about Heinlein--I'll have to recheck. Lots of real good "Heinleinia" included in that one. Spider worshipped the ground Heinlein walked on, with good reason.
If you've not read Spider Robinson's Callahan's Key you're in for quite a treat, and you'll run across several old friends you may have encountered before...including a cat named Pixel who can walk through walls....
I just know I've heard that name before someplace...
