(SPOILER) heory: Sans pranked Flowey across time and space

So you know how when you get into Sans' (Sans's?) room Papyrus comes and asks you if Sans is pranking you across time and space? Most people assume this to mean Papyrus knows about the resets. But what I find interesting is the other thing he says:

"I hate it when he does that"

This means he's done it before, but to whom? It has to be to someone who has your ability to SAVE. And the only one other than you that can SAVE is Flowey. We know Flowey was a pacifist at first and talks to Papyrus right? He could have mentioned this to him explaining why he shouldn't tell Sans about him or why he doesn't go to Sans. Of course Papyrus tells Sans about Flowey but that's probably because Papyrus forgot or can't keep a secret.

What do you guys think?