I think i found the problem. Blender was exporting faces in incorrect format.
After few unsucessfull tries i read how the format works (
http://paulbourke.net/dataformats/obj/ ) and create my own "mvorigin" script.
But now, when i'm trying replicate the problem i can't replicate it. Now exports looks correctly (i didn't try import it, just as im looking into the file).