Fergie Fetes Josh Duhamel's B-Day

Low-key lovebirds Josh Duhamel and Fergie rang in his 35th birthday Wednesday night at L.A.'s Hana Sushi.

"They were really cute, totally laid-back," said one eyewitness, (No VIP room for these two – they sat in the main dining room just like any other couple.)

Playing the good girlfriend, the songstress even "asked if the restaurant did something [special] for birthdays," adds the onlooker. "So they brought out some dessert for him and sang."