Robert_Charlton - 7:40 am on Jul 4, 2013 (gmt 0)
>>different data centers... noticeable during rollouts<<
ZydoSEO and reseller - This in all likelihood explains the results I mention above (which turns out to have been more recent than six months ago).
Checking my calendar, I see that I was at BestBuy on the evening of March 22, 2013... and SearchEngineLand [searchengineland.com...] reports a Google announcement of the Panda 3.4 rollout on March 23. That's close enough for me.