If ever there is a hiccup and something that should be linking doesn't link, you can run Rebuild Post Cache to update the post cache, but you shouldn't find yourself needing to do that often. Not sure if it is a point of confusion, so just in case, I'll try to explain the Ajax thing. On full replies
GAL
can auto-link right as soon as you post, as that is a full page request, but with Ajax Quick Reply, it is a partial page request, so while
GAL
knows whether something needs to be auto-linked, the actual link doesn't show until the next time around. That is not something for which you should be running Rebuild Post Cache.