Might be …
https://www.facebook.com/tednugent/ has no checkmark
https://www.facebook.com/tednugent/posts/10157067026607297?comment_id=10157067260212297¬if_id=1577908822347430¬if_t=feed_comment_reply has the blue checkmark.
I don't "DO" FB, but it seems odd that the same post would both have it and NOT have it.