Many of the tabs in the current profile have indicators, which highlight recent activity in the tab:
Opening the tab will highlight the recent activity for you.
I feel that the votes tab may be a non intrusive way to accomplish this. Basically, posts with downvotes or closevotes behave like starred posts, except that the changes are tracked in the votes tab, with the votes tab being given its own indicator.
For this, we will probably need a "recent" subtab on the votes tab. This will list all posts which you have downvoted or closevoted (sorted by time of last activity), and all the posts with changes that you have not seen (i.e, weren't there when you last opened the tab) will be highlighted.