missing ocsp-requests


in https-tests we find one (or two for EV-certs) ocsp-requests in waterfall.
e. g. http://www.webpagetest.org/result/130903_3X_CQQ/

We watched this on our agent (wptdriver 130) with wireshark and there is only this single ocsp-request sent while wpt-test is running. If we call the same url of the script manually in the same FF, we are watching a lot more of ocsp-requests (about 24). We tried manually with all the FF-preferences set, the wpt-agent uses in the FF-profile. Same result: More than 20 ocsp-requests.
Any ideas, why most of the ocsp-requests aren’t visible in the waterfall?

Regards, Nils