duolingo whirligig at top left of page
Is that thing always supposed to spin? I haven't noticed as I have been focused on the lessons. Also at the end of a lesson the page froze and the whirligig continued spinning. I finally closed the session. I cannot remember if the lesson was a repeat nor which one in the series I was on.
Possibly a momentary network dropout on my end. It went on for quite a few minutes. I think it because of unresponsiveness I posted a comment more than once, and later removed the repeats. But I have seen these delays before, at the end of a lesson.