Aww how cute!

Fresh off the heels of their trip to Australia, Benji Madden wished his lady love Cameron Diaz a happy 43rd birthday on Instagram.

Along with the sweet snap, Benji wrote, "Happy Birthday to my Beautiful Wife❤My best friend and Everything else- there's so much I could write. I'm the luckiest guy alive- I get to spend the rest of my life right here. I love this Woman!!❤️Many more Baby!! ❤️ 🎁🎉🎂"

It may have been a coincidence that the Good Charlotte musician called her "Baby" in the post or perhaps it was a tiny nod to the rumors swirling that the 43-year-old is pregnant!

The duo have been inseparable since they were married secretly back in January. Despite their hush hush romance -- things seem to be going along swimmingly!

Yesterday, the couple arrived at LAX after filming The Voice's grand finale in Australia. The duo jetted out of Sydney on Monday morning and back to Los Angeles. Even though he was on duty working -- it seems as though the musician wanted his lady love by his side -- maybe it's because he knows she's got a bun in the oven!