Warner, a BYU verbal-commit, told FOX Sports NEXT just a few days later at Dana Hills AirStrike that it's an offer he'll have to take into consideration.
"It was kind of surprising because I didn't have much contact with them," Warner explained. "That's a big time school so it was a good offer."
Warner said the Trojans made a stop at Mission Hills to watch spring practice about a month before offering. When he received the offer he was told by USC the entire staff finally got a chance to watch his film and collectively decided they liked what they saw.
"They said the whole staff sat down and watched the film and took my junior season film and said the really liked me and needed to offer me," Warner said.
"I talked to [offensive line] coach [Mike] Summers," he continued. "It was short and sweet. He wanted to make sure I knew I had the offer."
The 6-foot-3 205-pound linebacker says he is still thinking about his recruitment, but says "he's cool" with where he is now, committed to BYU. "There are things to think about, it's great to have [the USC] offer, I'm blessed to have it.
"I visited and fell in love with BYU, that's why I committed there," Warner said.
As of Saturday at Dana Hills, Warner hadn't spoken to the USC staff since receiving the offer.