If slippage off the sear without the trigger being pulled is cause for an unintended discharge, there is more of a flaw that a rough finish.
1911 without firing pin block are easy to get to go bang when dropped, and non-series 80 / Schwarz fixes are analog rather than digital in nature (lighter/shorter firing pin). But, one does not expect a 1911 to be drop safe.
1911's with a firing pin block safety can even go off without being dropped if they are sucked into an MRI machine (Bartell et. al., 2001, AM journal of Rotenology,
http://www.t.supertrap.com/ST_Downloads_files/GUN_in_MRI.pdf). Small world - I still have the Milt Sparks summer special holster bill sold me in the 80's.
Also, the last I heard, Sig does not certify one as an "Expert" on their guns, but as a "Certified armorer" - a very real distinction.