Yes, looks custom to me, too and possibly from one of the Santa Barbara notable builders, but which one I can't say.
Some ambiguities: the early Columbus decal is odd on a frame with these forged semi-vertical DOs (Guessing they are Shimano?) as is that pump peg, but other things to note: no WB bosses, nutted brakes, apparently a Cinelli "can-opener" BB shell (TBC), paint may not be original (but might be) and might be Imron.
Lugs look thinned, seat cluster is very nicely detailed...it's the work of somebody who knew what they were doing, but didn't bother to "sign" this work...