Is it normal to congratulate someone on their birthday?
Let me explain. This guy gave his number just because we work together. He doesn't have my number. I have his number for months now, but I haven't had any need to call him yet. We talk, but not a whole lot. He never told me his date of birth. But I saw his date of birth written down on the board (related to a company sports event).
Would it be normal if I sent him a Happy Birthday text message from my phone (a number he doesn't know: because we only talk in person, and he doesn't have my phone, and he doesn't have my social media)? Or would that come across as me being obsessive or creepy? Would he start to wonder how I know his birthday? Where I got his number? (Because it has been months since he gave everyone his number, and I never called him, and maybe he forgot giving his number). I feel like I am overthinking this because I like him and we flirt sometimes.
I'm also not a 100% sure that date is his correct date of birth, because I got it from the board at the office. Not from him directly.
I considered just congratulating him in person, because that is how we talk. But I don't have any valid reason to be at the office that day. I'm not even sure if he's going to be at the office that day. And so texting is the easiest way to congratulate him without making myself look like an idiot through the company email.
Help. Please send advice.