You're not giving us a lot of clues, but that looks like a repeat of part of the pattern from the back. If you open the obj in UVMapper again, go through each of the 'Select by Material' options, and you should find that part showing up in the wrong group. Alternatively, if you've got the Pro version, you can save a coloured and labelled version of the map .. again look for that side part in the wrong material group. Or just post the map here (or a link to it). Unless you've got loose polys which are actually laying on top of the mesh, the map will hold the answer.