To me, this is a question about exercising power in the community, so I would start by asking permission. If you don't ask, you are dis-empowering the member. By asking, you are empowering them by giving them control over your action. And I believe that members should feel empowered.
Asking also changes the nature of the relationship from "either you or I decide who crafts the title" to "let's work together to craft a better title." By inviting them into the process of re-crafting the title, you are working together toward a common goal. And, in the process, they may incidentally learn more about your own personal goals and adapt to accommodate.
Finally, it's just a great excuse to start a dialogue with someone. Surely there would be a way to share a story or two in the exchange.
Of course, there is the danger of the author not responding. In a case like that, I would give her or him enough time to reply, and if they didn't I would move on to "I decided to go ahead and make the change."