01/06/2013 at 03:00 PM EST
didn't necessarily have the wildest of birthday celebrations, but his special day certainly didn't go unnoticed.
The Silver Linings Playbook star
, who flew in on Bombardier's Hollywood Reporter
Palm Springs shuttle from Santa Monica, Calif., and turned 38 on Saturday, was greeted by a slew of screaming fans when he arrived on the red carpet at the 24th Annual Palm Springs International Film Festival Awards Gala in Palm Springs, Calif.
"Bradley started interacting with his fans and then they broke out into song, chanting 'Happy birthday to you,'" an onlooker tells PEOPLE.
Running late into the event because of the fan holdup, Cooper whisked by many of the reporters, and when asked about his birthday plans, answered with a smile, "I'm here!"
But the birthday surprises didn't end there.
After being honored with a Desert Palm Achievement Award presented by Playbook
director David O. Russell, PEOPLE's former Sexiest Man Alive
was given a shoutout by event host Mary Hart, who insisted the entire room sing "Happy Birthday" to the actor.
"It seemed very unexpected," the onlooker adds. "He seemed a little shy and embarrassed by it, but while managing to smile still."
– Dahvi Shira