I have notice something strange, every time I correct a bug or make a small change to a app then reload it to the phone, the size of the apk doubles or triples !, but if I uninstall the apk first then load, it show the right kb or mb size.
My apk in the computer is 16mb but when reloaded (not a new install) it shows 42mb in the phone.
16 MB is a massive apk? What files are you adding?
The apk size itself should remain fairly constant unless you are running a script or something to add new files on each build.