The U.S. State Department released aggregate New START numbers from the 1 September 2014 data exchange. Compared to March 2014, Russia substantially increased the number of deployed launchers - from 498 to 528 - and deployed warheads - from 1512 to 1643. The total number of launchers increased as well, but not nearly as dramatically - from 905 in March 2014 to 911 in September 2014.
Where did the new 30 deployed launchers and 131 warheads come from? Most likely from the two Project 955 Borey submarine. Two submarines can carry 32 Bulava missiles with as many as 6 warheads each - this alone could have added 192 warheads. However, it is unlikely that both submarines had a full missile load on September 1, 2014 - Vladimir Monomakh conducted a test launch on September 10, 2014 and it appears that it was the only missile on board. But Yuri Dolgorukiy appears to be fully loaded (or nearly so) - it is expected to conduct a test launch in October 2014 with a full complement of missiles on board. The bottom line is that SLBMs can account for 17 launchers and up to 102 warheads (we don't know if Bulava in fact carries six warheads as was declared in START).
Then there are ICBMs. Two silo-based RS-24 Yars missiles were installed in silos in Kozelsk in August 2014 - that would add two missiles and eight warheads. In September 2014 the Rocket Forces announced that in addition to the regiment in Kozelsk, two mobile RS-24 Yars regiments will be deployed by the end of 2014 - in Nizhniy Tagil and Novosibirsk. That would be as many as 18 missiles with 72 warheads. Some (and definitely not all) of these missiles may have been already New START accountable in September. Withdrawal of single-warhead SS-25 Topol ICBMs would account for the moderate increase in the number of total launchers.
It would take a closer look at the numbers to see if all this adds up, but it appears that there is no mystery in Russia's New START numbers.
U.S. numbers in September 2014 are 794 deployed launchers (778 in March 2014), 1642 (1585) deployed warheads, and 912 (952) total launchers.