Manuscript Preparation, Copyediting, and Proofreading
Q. For text following a long block quotation, is it a must to indent, even if adding a single line? It seems confusing (visually) to do so.
A. Indent only if you are starting a new paragraph. If the text continues the paragraph that precedes the block quotation, then it should begin with no indent. Please see CMOS 13.24.