Chapter 5.1.1 describes stepping algorithm as: ... 13. Invoke the user intervention G4UserSteppingAction. 14. Handle hit information. ... This items should be in reverse order - user intervention after handling hit/digi information. See the code at http://www-geant4.kek.jp/lxr/source/tracking/src/G4SteppingManager.cc#L230
Thanks for pointing this out! It will be fixed in the forthcoming documentation for release 10.3.