Flash 10 :: Bitmaps Less Then 4px In Width / Height Not Working?

I've come to notice recently while using bitmap objects in the Flash CS5 (maybe before as well) authoring environment that are less than 4 pixels in width and/or height that they are treated as though they are 4 pixels wide/tall. Many of the bitmaps I use are 1 px wide in one direction or the other, and they are stretched to fill an area. Lets say I have a bitmap that is 20px tall and 1 px wide, and I stretch it to be 100px wide. The "hit area" of the object, or parent objects that contain it, is 400 px wide. So even if you click a significant distance away from the object, it is still selected, and anything underneath that invisible area can't be selected.

I've also noticed that when exporting a frame as an image, the smallest the width/height may be is 4px, and when I click the Edit button in the Properties panel with a Bitmap instance selected, it opens up in Photoshop CS5 and is 4 pixels wide! I'm wondering if for some reason Flash can't handle bitmaps less than 4 pixels in width/height and is treating it as if it IS 4 pixels wide, possibly even adding 3 extra columns of transparent pixels, because if I do the same thing manually, naturally it acts identical to the way Flash treats the 1px wide version. But why? Why can't Flash handle small bitmaps? Seems to me that's more efficient than quadrupling the amount of memory required.