HTTP Referer Errors in ArcGIS Server www.geocortex.com

Can anyone explain to me why I keep seeing 'HTTP referer: http://www.geocortex.com' up and down my ArcGIS Server logs? I am using Secured REST services in my viewers. 

 

Also, in my config.xml file I see 'http://www.geocortex.net/security/claims/category/user'? Is my site making calls to a geocortex site each time it loads? If so, why?

 

GE 4.5.0

 

HTML5 2.6.0

 

ArcServer 10.4

 

Thanks,

 

Mark