How could Mary say that just from meeting Anna, Michael, and Uriel? They were all terrible to her, Anna tried to kill her, Dean told her they were all dicks, why would she suddenly feel the urge to tell her son that angels are watching over him, as in guardians?
She met Castiel. He was in 1978…
Um, what? No, this is completely wrong, sorry. Michael wiped her and John’s memories completely so they wouldn’t remember meeting the angels or Sam and Dean, or remember what the boys told them.
“Angels are watching over you” probably stayed as a slightly creepy subconscious remnant of the wiped memories, the subliminal fingerprint on her mind of angels without any conscious awareness of the experiences.



