I agree with @brew_cat. At this point in fermentation the yeast has likely taken care of the sugars. Now, the yeast is cleaning up byproducts of fermentation such as diacetyl, aldehydes, and sulfurs.
If your temps drop too low now the yeast will flocculate out, and skip cleaning up those byproducts. Although the first 72-96 hours is the most important for yeast temp control, you have to also be concerned of dropping temps towards the end so the yeast have time to clean up after their party.