Every so often my fingers slip when entering grades, and a score that is way over the maximum points is entered (ie: a 10 pt assignment may have a student earning a 9.5 but if I miskey the decimal point or they keyboard doesn't acknowledge the input, it quickly becomes a 95 - this greatly skews the overall grade). 

If a prompt came up, it would be a nice verification - Yes... this student earned a few extra points and the grade is correct OR No.. oops, glad I caught that mistake before the grade was posted.