Maybe they're combining both 10.3.0 with 10.4.0 and release it as one update? Or maybe they forgot....
EDIT: This is exactly....how I imagine the conversation between some staff members at RiliSoft.
*Rilisoft goes on their facebook page.*
Worker at Rilisoff: What the heck?! Why on earth is our facebook page being spammed?!
Co-worker: Judging by the posts, I guess we forgot to release the update for the windows users.
co-worker 2: I thought we had somebody that made sure that the new update got to the Appstore/Playstore?
Co-worker 1: Yeah, that's Toms job. He makes sure that they get released as soon as possible. Let me ask him. TOM! Did you not send off the update to windows so they could release it in the store?!
Tom: What window?! The window you look out of?! *Takes a minute to realize what he has done* Oh........That window......Well,uh.....I forgot.
Co-work 1 and 2: DANG IT TOM! Now the windows players are two updates behind!
I really think they either forgot,still working on it,or planning to release both updates in one.