It has been awhile, but on mine let it update. Mine now uses 13.1 instead of 13.
Thank you for your kind help. I think the install window box was off line too long. I think the solution wasthis: while I was on WIFI Ineeded to keep letting it try to install the update until it really did. . .I think it really did this time. I opened and shut my program 5 times. So far the notice hasn't appeared again when the startup was taking place. Thank you again for your kind help.