convergence

[Lune]

Can anyone explains what this warning means
wARNING: NODE 3 INSTANCE CONC-1 ON SURFACE ASSEMBLY_ALLCONCSURF HAS FACETS
WITH NORMAL VECTORS DIFFERING BY MORE THAN 30 DEGREES. CONVERGENCE DIFFICULTIES MAY OCCUR AT THIS NODE WITH FINITE-SLIDING CONTACT.
THE NORMAL CONTACT DIRECTION AT THIS NODE WILL BE (0.0000,-0.70711,0.70711).

 

[portliner]

It sounds as if the mesh is too coarse, the normal varies greatly over the element-face