I would just say happy birthday and see how he responds. I sent my H a text on his birthday, but considering we were actually separated at that point I may not be the best person to ask.
Now I"m off to go have fun with friends who aren't close. Have a good evening!!
Me42, H40 D12, S8, S7 A revealed: 7/13 Sep 4/14; Agreed to D 1/15