That depends on:
- whether there's anything else to fix that the editor simply left out, and
- whether you feel that the suggested title is an improvement
If the edit is too minor, simply reject it as such. Edits shouldn't just focus on the title, but also the post body and tags, if possible.
If the new title isn't any better than the old one, but just phrased as a question, I would probably reject it. There's no definitive guideline on how titles should be written. See: How do I write a good title? – basically, some people say questions in titles are redundant and not needed, while others say they make the titles more readable.
I personally like a "How do I foo the bar in Yak?" better than "Foo a bar in Yak", and much better than "Yak: Foo a bar", but ultimately this still comes down to personal preference.