Glancing down, his eyes widened.
The Class of 2016 offensive tackle had gained nearly 80 Twitter followers in the last 20 minutes.
"That's when I knew something was up," Mathews told InsideTennessee. "People were tweeting congrats and stuff like that at me. I didn't know what for yet."
Mathews soon received a call from his coach at Brentwood Academy (Tenn.) telling him to phone to Tennessee linebackers coach Tommy Thigpen – his primary recruiter and the man who would extend him his first scholarship offer.
The 6-foot-6, 260-pounder said the Vols' offer came as a "surprise," but a good one at that.
"It was a huge deal. I mean, it was my first offer. I just feel very humbled and blessed by it. It's just incredible," Mathews said. "Tennessee has shown interest in me before, but I didn't think they'd offer me for, like, maybe in a year from now. It was very surprising."
Hours after pulling in his first offer from the Vols, Ole Miss followed suit.
"I really didn't see that one coming," Mathews said of his Ole Miss offer. "That was a way bigger surprise. I had only talked to them once on the phone before. I didn't even think they knew who I was."
While the long tackle has already tripped to Knoxville once this spring for a junior day event, he said he wants to keep learning more about the Tennessee program.
"It's just a big-time place," Mathews told IT. "I really like what they have going on there."
Growing up in Nashville just a few hours west of Knoxville, Mathews knows plenty about the Vols' feverish following and "rich" traditions.
Mathews said he is a Texas A&M fan because both of his parents went there, but Tennessee is a close second.
"Everyone around here loves the Vols. It's everywhere. You can't ignore it even if you tried," Mathews said. "I've always paid attention to them and watched them like my whole life. I mean, I pull for them unless they're playing A&M."
Mathews said his favorite part of his recent visit to Knoxville was getting to speak briefly with Tennessee head coach Butch Jones, who convinced Mathews' that the Vols would be back to their winning ways again soon.
"I think coach Jones is the right guy. He's doing a great job up there. When he was talking to us at the junior day he was really convincing saying we're going to get this thing turned around," Mathews told IT. "I believe him for sure. It's going to be a really good program here really soon."
Mathews, who is teammates with fellow Tennessee offer Ryan Johnson, said the two big factors in his still-young recruitment will be staying close to home and early playing time.