I have two SAE in my 29 gal community tank, and at times, no matter how long I search, can only see one.
Then out of the blue, both will be there hanging on the glass or sucking on a plant for the algea.
The fake driftwood thing I got has a lot of holes in it (it's hollow to a certain extent); have noticed the SAE's in one of the holes looking out at the world. Methinks your CAE was playing hide n go seek on you!