Late TikToker Caleb Graves Was 'Worried' About Half Marathon Before Collapsing at Finish Line

Bobby Graves, who went by Caleb on his popular TikTok account, expressed concern about the Disneyland Half Marathon ... a day before he collapsed at the finish line and died shortly afterward.

The late internet personality uploaded a video to his 18K followers hours before the race, saying he was "marginally worried" due to the raging heatwave in Southern California.

As the temperature in Anaheim reached triple digits, Caleb said he was nervous about participating in the theme park's Halloween Half Marathon, given his "susceptibility" to heat.

He continued ... "I have some susceptibility, I don't know if it's temporary or long-term, to heat. Because I was outside for like 20 minutes, walking my dog, and it was hot, but I felt fine ... and then like 10 minutes after I got back in, I just passed out."

Caleb told his followers that he had "no control over [his] body" at the time, and that he wasn't sure what was going on ... but speculated he was struggling with "heat exhaustion."

Sadly, Caleb finished the race, but did not survive the day ... Anaheim Police Sgt. Matt Sutter confirmed the internet personality had a health crisis after finishing the half marathon at 7 AM -- just 2 hours after the race kicked off.

Caleb was immediately tended to by emergency personnel on the scene, who applied life-saving measures as the runner experienced cardiac arrest. He was taken to a nearby hospital, where he was pronounced dead.

Fans are now clamoring for answers ... pointing the finger at Disney for holding the race despite the dangerous heat.

Caleb's autopsy is being handled by the Orange County Coroner's Office ... which will release a report in the future.

The TikToker was only 35.