I think she had. When she was on Namek, she thought about how 悟空 became a handsome guy... After, at the end of Buu Saga, Chichi told she had a crush for 悟空 and she though again about it, not giving a clear answer. Maybe it wasn't a big crush, but surely 悟空 has a special place in Bulma's heart.
In her teenage years Bulma is attracted to every goog-looking guys she sees. In the 23rd WMAT she exclaimed how handsome 悟空 has become and wished she was a few years younger. So MAYBE she used to have a crush onhim, but a BIG 'maybe'. Now he's her best friend, he's a very important to her but she doesn't 爱情 him romantically anymore ( if she has ever really felt that way about 悟空 ).