That's when the Panthers running back's life took a sudden turn.
He witnessed 72-year-old Dan Smoker Sr. tumble off the side of a cliff and fall, almost certainly to his death.
It turned out he wasn't dead, but Smoker was in big trouble, with a raft of internal injuries.
McCaffrey called 911 and his buddy and brother helped attend to Smoker and his 13-year-old grandson, who had also been along for the hike.
Eleven minutes later paramedics arrived on the scene.
After five and a half weeks in the hospital, Smoker has now recovered and the families have kept in touch.
In fact, at McCaffrey's invite, the Smokers will attend a Panthers game this season in Charlotte.
Michael Mann, @run__cmc and @notoriousmax25 are great football players, but even better humans. Yesterday, they helped save my dads life after he fell off of Castle Rock. They comforted my son when he was alone. Then showed up at the hospital to check in. @AdamSchefter @espn pic.twitter.com/MVAdbr2gYV— Dan Smoker (@dsmokexu) March 4, 2018
When the @Panthers said they were sending a gift basket, I thought it'd be some chocolates. This certainly went above and beyond! Panthers and @run__cmc, Eli and dad can't wait to come see y'all play! #KeepPounding #SmokerStrong pic.twitter.com/a6RO9dNjkp— Dan Smoker (@dsmokexu) May 2, 2018
Monday, McCaffrey spoke at length about the incident and how it's impacted his life.