After stepping out in New York City last month, Ryan Reynolds and Scarlett Johansson were back in action on the opposite coast Monday night, catching the Damnwells' show at the Troubadour in West Hollywood.
Reynolds, 30, and Johansson, 22, arrived separately, an observer tells PEOPLE, and greeted each other with a hug and a kiss on the lips.
"In the foyer they were talking and had their hands all over each other," says the source. "He kissed her a couple more times in the club. He was totally sweet. She went to the restroom and he went to check up on her."
The pair watched the show with the rest of the crowd, although the witness says fellow concertgoers recognized them: "You can't help but recognize him because he's tall. She had a hat on and was so tiny."
After the show, they hung out at the club for a while before they called it a night – after Reynolds poked his head outside to check for paparazzi – and left, hand in hand.
Johansson and Reynolds (who ended his engagement to Alanis Morissette in February) spent Easter weekend together in Manhattan, where an observer at one restaurant noted: "They were a cute couple!"