I am working on a model. I used the short cut of modeling half of it and then duplication with symmetry to get the other half. It worked very well, but I deleted one of the halves to further work on it then I duplicated it again and welded both halves together, but this time some of my polygons got there normals kind of messed up, easy enough, select the offending polygons and revers there normals. Well it dose fix the problem, but when I close the file and reopen it, it's back to the same problem. Have I stumbled on to a vertex modeling bug or am I missing something else? Any help will be appreciated greatly.