"I went to the special room upstairs," the British actor told late-night TV host Jimmy Fallon (quote via Hollywood.com). "There was a guy there in a baseball cap and he was just playing guitars. He was kinda one of those guitar people who just seem really impressive, but he just seemed like a normal guy and was really sweet."
The two sat down and played a few chords, with Brad graciously offering to help the novice guitar player pick out an instrument. But the young actor left the store, never realizing he'd been talking to a world-famous musician.
"Every single time I touched a guitar [the employees] were like, 'Do you want Brad to just play it?' I was like, 'Well ... ' I just thought it was a guy who worked there. I just had no idea who he was ... I bought a couple little instruments and that was that."
Brad was recently announced as one of the headliners for Country Thunder in 2013, alongside Dierks Bentley, Keith Urban and Lady Antebellum. He'll also spend the next few months finishing up his new album, which he is recording in his home studio.