When looking at my flag-responses page, it's not always easy to tell what's new. Sometimes flags take a while to resolve, so I might have one farther down the page that only now got resolved. Moderators have always been able to leave messages for declined flags and now can leave them for helpful flags too. If the moderators took the time to write them, we should try to read them. But right now all I can do is scan the page and see if anything new jumps out at me.
For other types of responses (comments, edits, reputation changes, even changes in favorites), the new information is highlighted through styling (background color). Could we do something like that for the flags page too? Or provide some other way for users to see their newly-handled flags?