I think it is weird. To be honest, if I were you, I'd find it unsettling.
Names have associations for people -- it's the reason why very few people in Britain will ever call their son Ebenezer. There are some lovely names I would never use for my DC because they were the names of certain bullies I went to school with, and those names instantaneously conjure up those connections in my mind.
So I would question why an ex-boyfriend would make such a decision because, as soon as the name was even mentioned, the first thing he would have thought was that he once had a serious girlfriend/fiancée by that name. Who would want to call their child by a name that had such associations?
But then, something similar happened to me about twenty three years ago. A friend of my then boyfriend had a child and gave the child the same name as me. My name is not particularly usual, so it was obvious that he had got the name from knowing me, and, at the time, I just thought it was sweet.
Then, about ten years ago, I bumped into this friend in a pub. We started chatting and he told me straight: "I named my daughter after you."
I am afraid it made me feel quite uncomfortable when he said that. After all that time (he probably hadn't seen me for about thirteen years), and over a decade of his daughter having the name, he still had a strong association between me and that name -- enough to mention it when I bumped into him. It creeped me out a bit, to be honest, as though there was something I didn't know.
But I tell you what is really creepy ... ex-boyfriends using your name or your phone number as new computer passwords nearly a decade after you originally split up.