Joined: Jul 2015
Posts: 7,361
Likes: 3,217
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
if he or she isn't "certain", then i'd go elsewhere.
5mm is less than 1/4"... steel either bends, or it doesn't... 5mm is a minor tweak, and it won't mysteriously "revert".
go elsewhere.