Low volume and lighter-than-normal liquidity left US bond markets more impressionable than normal today.  Or perhaps it IS normal given that it's a data-free Monday in the middle of May and the day after Mother's Day.  Those details would logically keep a few extra traders out of the office.

Fewer traders means each trader accounts for a bigger-than-normal piece of the pie.  Thus, light liquidity can increase volatility if said traders are trying to get somewhere in terms of trading levels.  That wasn't necessarily the case today, but bonds were nonetheless influenced more than they otherwise might have been by some central banker comments and by bond issuance.

The central bank in question is European this time around, as ECB's Villeroy talked hawkishly about how the ECB would ultimately begin winding down stimulus.  This was a bigger deal for European bond markets, logically, but domestic markets took a hit as well.  Later in the domestic session, corporate bond issuance added pressure to Treasuries.  Finally, tradeflows and technicals kicked-off an afternoon drift that took 10yr yields over 3.0%.