Beyonce and Gwyneth Paltrow attends The 53rd Annual GRAMMY Awards held at Staples Center on February 13, 2011 in Los Angeles, California. Credit: Kevin Mazur/

Blue Ivy's mama is one year older!

Beyonce marked her 31st birthday on Tuesday Sept. 4, her first since becoming a mother to daughter Blue Ivy Carter, 9 months.

No word yet on exactly how the "I Was Here" singer celebrated her special day, but the superstar's website was adorned Tuesday with handwritten notes from her nearest and dearest -- including close friend Gwyneth Paltrow and family.

"For Dear Sweet BB on her 31st birthday," the Oscar-winning actress, 39, writes. "We love you so very much."

Signing off with a "Love," the Contagion star then left her signature -- as did husband Chris Martin and even their kids Apple, 8, and Moses, 6. Other well-wishers leaving their handwritten birthday notes? Her mom Tina Knowles ("God blessed me with one of the greatest gifts in my life on Sept. 4, 1981."), sister Solange ("[We] have one heart"), her mother-in-law ("You came into my life a sweet Southern girl . . . You've blossomed into an amazing woman") and others.

Beyonce and hubby Jay-Z have been pals with Paltrow and the Coldplay rocker Martin, 35, for over a decade.

Back in February, Paltrow predicted big things for just-born Blue. "She is going to be an entertainer," Gwyneth Paltrow said. "She just has this glow around her like her mother."