Sometimes one finds the answer to a question while asking it or briefly afterwards, and after having posted it there's not much of a reason for others to more or less just repeat the answer. The 48h self-accepting limit makes sense, but one may have forgotten about the question after two days, so a notification à la
You can now accept your self-answer to
<question title here>
at least when no other (updvoted) answer is there would be helpful.