I don’t think so. From a UI standpoint, it’s a somewhat inconsistent choice of style if that’s truly what it is.
I was the one who had initially suggested the last visit bar be blue, and I noticed that when they went forward with this change, they had only changed the color for the bar in topics until three days later when they updated both.
I still believe this most likely occurred due to an update they rolled out, which brought the red bar back.