I know, sheesh another speedo question

I looked around on the search function about this issue, but nothing really pertained to my speedo. Mine works, but the needle moves slowly. If I come to a rapid stop from 50 mph, the needle is still coming down to 0 after I've stopped. My '93 K11RS had the same occasional issue, it would ending up correcting itself. I'm curious as to why. My K75 speedo worked well when I last rode it, about 6 weeks ago.
I've got a winter list of maintenance items to get to. My gear indicator is only showing 3 & 4. I'll be relubing the final drive, need to take it in for a clutch spline lube, so the speedo is on the list.
Thanks for any responses.