Warnings with G4PathFinder::ReportMove()

Dear Geant4 users,

For a radioprotection simulation, I defined some concrete blocks (in magenta) and I used a scorer mesh in a parallel geometry (in grey).

However, during the simulation, I have a lot of warnings:

-------- WWWW ------- G4Exception-START -------- WWWW -------
*** G4Exception : GeomNav1002
issued by : G4PathFinder::ReportMove()
Endpoint moved between value returned by ComputeStep() and call to Locate().
Change of (End) Position / G4PathFinder::Locate is 1.00000036152755e-07 mm long
and its vector is (-9.922541721607558e-08,-1.114705128202331e-08,-5.483343556988984e-09) mm
Endpoint of ComputeStep() was (1117.800000099226,-230.9971355447562,2546.949761772873)
and current position to locate is (1117.8,-230.9971355559033,2546.94976176739)
*** This is just a warning message. ***
-------- WWWW -------- G4Exception-END --------- WWWW -------

I read the same message in an old post (http://hypernews.slac.stanford.edu/HyperNews/geant4/get/analysis/553.html) but I have no more information. Do you have an idea of the problem? How it impacts my results? I use version 10.4 of Geant.

Thank you in advance for your help.