Everyone knew that heroes missed birthdays, weddings, funerals - sometimes even their own - because the world was coming to an end. No one talked about things missed or ignored because he was too damn tired to think about anything except sleeping, or working on the armor, or catching up with Stark Industries, or just didn't care about the date because he was busy.
He hoped everyone - Pepper - was proud of the fact that he wasn't losing track of dates because he was drunk. Then again, he had never been good with dates anyways, so it probably didn't come as a sharp shock he'd forgotten about his own birthday.
"Why not California?" he asked, wandering purposely over to check the weather, circling the kitchen's island to take in everything scrolling along the smart-screens. "Sunny. Warm. Earlier, so we can fly and still be there now. And great sushi right on the beach so you can wear a tiny little something." And he could wander around without people staring at the nightlight in his chest. Good plan.