As it says below "You need to look at the download size on the end user device, not the binary size in iTunesConnect."
Is that what you are doing?
Because otherwise, it includes the bitcode size.
(i don't pretend this makes sense. only that it is :P)
In any case, i would still bet more heavily on it being displayed wrong than anything else.
If i was to increase the binary size of first party apps at google by even 1%, there would be a mob with pitchforks at my desk in less than an hour.
I can't imagine apple is really different.