Symbols are incorrectly sized when Area Text element in Symbol Definition

Create a simple Area Text element by selecting the Text Tool and dragging a rectangle around 80 x 20 px.
In the Area Type options, inset the text by 2px and align vertically by EM height centered. Set the width to 80px and the height to 16px. Turn off the Resize Option. 

Notice that the Area Text element is 15.994 px tall even though you manually entered `16px and wanted it to be exactly 16px. This is typical and frustrating, but not the issue at hand.

Now press F8 to create a symbol from the Area Text element. Align upper left corner and make it a Movie Clip.

The size of the symbol instance is 20.3445px  Though the Area Text element is the only thing in the symbol definition and it’s roughly 16px tall.

NOTE: I was thinking that the inset value (2px) may have been what was throwing the symbol definition off since 16+2 (top) + 2 (bottom) = 20, but you can see that the inset is already calculated in the text area element’s size.