If an average trading day is a 5 on a 1-10 scale, yesterday (Tuesday) would have been a 1 in terms of volume and liquidity.  Today's number would only be 2 to 2.5, but it's hard to find anything else to criticize when yields are the lowest they've been in months.  A stronger rally in Europe certainly isn't hurting, and moderation in oil prices (or at least friendly headlines) might be helping.  

Today's only relevant scheduled event for the bond market is the 5yr Treasury auction at 1pm ET.  Yesterday's 2yr auction actually managed to have an impact, so it wouldn't be a surprise to see a reaction to today's offering.