Bonds had a rotten day, primarily because stocks had an amazing day (although the terrible 5yr Treasury auction didn't help).  In turn, stocks primarily had an amazing day because they had a rotten day on Monday.  Looked at another way, in week-over-week terms, the S&P is roughly 2% higher right now--something that has happened to 1 in 4 weeks in 2018.

Caveats aside, and holiday trading realities notwithstanding, there are a few reasons to be cautious about this particular move.  First off, in outright terms (not percentages), today's stock gains were the best ever (Dow, S&P).  Volume was nearly as high as last Wednesday's Fed day.  That suggests some investors may be lurking and waiting to get back on-board with stocks as soon as they sense the Q4-2018 dip is over.

Beyond that, bonds have had their best 2 months in more than 2 years.  It's highly uncommon for 2 such months to be followed by gains in the 3rd month.  I think change to "new year trading" only makes that a bigger risk.