Gent's,
I wonder if the original owner didn't intend to bob the hammer spur for a smoother draw when pocket-carrying?
Maybe he added the serrations on the front of the hammer to increase thumb-purchase for single-action cocking, then just never got around to snipping off the hammer spur.
Whatever the reason, I don't see the added serrations hurting anything, other than maybe breaking the jaded heart of an overly-orthodox Colt collector.
I think the OP made a very fine deal on the little blaster. And lopping off the hammer spur would, in my opinion, only make the pocket gun more useful.
Happy trails,
-- Cary Gunn --