The default sorting in 'My Content' is 'Last Update Time' and it mostly works... but occasionally, a topic is updated and the sort order doesn't change.

For example:
http://imgur.com/DYg0Q

I notice this fairly often, because my first port of call is the 'My Content' page to keep up with discussions that I've taken part in. Often after I've clicked through all the threads in that list, I'll then go and browse the forums as usual and notice some day-old threads are marked with stars instead of dots (indicating that I've posted in them before).
If I then go back into 'My Content' and click through several pages, I'll eventually find the new topic (at the wrong place in the list).