Might be a browser issue, Marty. My read threads are highlighting as usual. I checked on Safari for iOS 6, Firefox for Mac 18.0, and Safari for Mac 6.0.2 (10.7 Lion). I cleared browser cache, cookies, etc. and opened new sessions for each. Once I clicked a thread, it showed up highlighted and stayed that way.
It's entirely a feature of 'remembered' links in your own computer. The links are highlighted because the browser finds them in your local links/history cache. They will no longer be highlighted (until revisited) after you clean up/delete your browsing history and/or temp internet files.
