The day is almost over so my take on it is probably too late. But, for the record, I think the only good time to have done it would have been when you had your daughter call him. That way you could have thrown in a happy birthday in a "by the way" tone. Look, it's obvious you wanted to tell him this, otherwise you wouldn't be asking if it's ok. And I actually think if you are at least on casual/cordial terms with the guy, if you don't do it, you look like you are overly angry and that's not something that would look attractive to him. There's a big difference too between saying a simple happy birthday and offering to take him out for it or buying him gifts.
M-34 XW-32 D-7 Found OM's presence 4/09 Separated 12/09 Divorced 8/10 GREAT relationship as coparents since 8/10