As a general rule, "over" implies concern, careful thinking or conflict. In the last case, there is often an underlying element driving a dispute. You may hear of court battles "over" the custody of children, or that there is debate "over" a controversial issue. There could be concern "over" a scientific finding, or hesitation "over" a choice. People dither and waver "over" difficult decisions. In all these cases, "over" indicates a relation of causality. In your example, a cause (the choice of a title) leads to an effect (hesitation). In this particular sense, "over" and "about" are often (but not always) interchangeable. You could say there is concern "over" or "about" an issue - the fundamental idea being that the "issue" is a driving cause for "concern".
"About" also implies connection with a subject. Ordinarily, this is a meaning of "about" that "over" does not carry. You could say that the book you are reading is "about" science, but saying the book is "over" science would hardly make any sense. You can talk "about" the stock market, but you cannot talk "over" the stock market. We learn "about" new ideas - in other words, we learn things that have a direct connection with those ideas. What you may have noticed is that, in these cases, the relation of causality no longer exists.
Keep in mind that this is not a hard and fast rule, as different verbs may require different prepositions, and different prepositions may carry different shades of meaning.