The blade is dragging the Oramask off its backing while it's cutting, as suggested. Woody has some great pointers.
When the outside edges are cut, the Oramask is well tacked down around the cut, but when the inside edges are cut, there is not much stick to anchor the Oramask against the drag of the blade, so the cut shape is pushed, especially around sharp corners. You can avoid some of that by selecting Line Segment Overcut in the dialog box where speed, force, etc is set -- it's under "More", as is Track Enhancing (which may also help). However, on very small text, Overcut could cut too far into the mask, actually cutting pieces off.
If the problem persists, the best bet, I think, is to cut the inside and outside as separate masks and then layer them.
For very small text, decals are the way to go.
Gene K