There was an issue in EA with high approval too early causing problems with companion quest and romance progression (especially for Gale) but I’ve not encountered this in full release. That said, I’ve not got high approval with Astarion specifically that quickly, so while I’ve not seen any cause for worry, perhaps someone who has will offer reassurance.

"You may call it 'nonsense' if you like, but I've heard nonsense, compared with which that would be as sensible as a dictionary!"