If the user tries to logout from the website by clicking the link,the home page is loaded as if the user have logged out from the website but the moment the page is refreshed the user is automatically logged in.After that user have to again click on logout link.This thing happens rarely, unable to understand as if it is a caching bug or not.
Since you are talking about a rare case, I cannot suggest anything more but additional testing. Try to pinpoint the bug, $logoutRedirect looks like potential source of the problem.