The overnight session was uneventful for Treasuries. Asian hours saw US 10's hold steady at very slightly weaker levels. European trading carried yields just a bit higher at first, but we've been in a moderate rally trend since 4am.
There are very few salient sources of motivation for the move apart from the fact that bond markets seem inclined to be hovering around long term range boundaries ahead of a week that's big enough to potentially break them.
If anything, Bank of England (BOE) Minutes and subsequent comments from Carney helped global bond markets in general. The BOE had talking about raising rates, but the Minutes painted them as less eager to do so. Carney's comments concerned a weaker labor market--the same sort of cautionary tone with which Yellen speaks of the US labor market.
10yr yields have worked their way down to 2.453 and Fannie 3.5s are up 2 ticks at 102-21. In a departure from recent connectivity with bonds, stocks are also improved, but only after spending the overnight session trading weaker. It's notable (and sort of a dead giveaway) that stocks and bonds both broke toward more positive levels after a huge central bank remained friendlier than expected with QE. (i.e. we see this consistently when the Fed, ECB, BOJ, or BOE embarks on or maintains their easy money policies, which benefit both stocks and bonds).