Flash of a Bullet in the top left corner of the search results

Question

I am using a UISearchDisplayController and SearchBar initialised from a nib. when the search is being run I get a flash of a small circle what looks like a "bullet" in the top left corner of the search results. [See attached screenshot]

It occurs in the simulator and on the device sporadically

I have looked through my nib and I am not adding any stray views and was wondering if anyone else had this issue or knows how to get rid of it?

thanks

@interface SearchTabViewController : UITableViewController