Seacrest, who is a big fan, spoke excitedly about attending the show on his Kiss-FM radio show earlier that day.
Watching the band from a garden box, the couple was "very snuggly and cute," an onlooker tells PEOPLE. "Ryan was singing in Julianne's ear."
"At Hollywood bowl watching Dave Matthews band w/my man @RyanSeacrest & bro @derekhough ran into my boyfriend @Phillips BEST night ever! :)," Hough Tweeted that night.
The dancer-actress – who graces the makeover issue of InStyle couldn't get enough of the performance and shared a series of photos of the band with followers.
Dave Mathews at the Hollywood bowl with my loves! :) frat time here instagr.am/p/PgDAxZif39/— Julianne Hough (@juliannehough) September 13, 2012
– Jennifer Garcia