Cookie created even when service invoked is stateless

I have an issue where a cookie is getting created even though the service being invoked is set to stateless. Each time we see the cookie created we also see a 403 OK message in the logs. This is intermittent. Anyone run into this?

IS 7.1.2
Updates
IS_7-1-2_WebSvcsXML_Fix8
IS_7-1-2_Core_Fix10
IS_7-1-2_SrvPrtcl_Fix8
IS_7-1-2_XA_Fix2

Thanks