Yeah, Otto, it’s a coincidence. Colombia is importing more from lots of countries, not just the USA.
All figures from here. 2014 numbers are just through October, so that decrease is likely to disappear in final figures. As you can see, the big winners since 2010 have been Mexico (free trade agreement since 1995) and China (no free trade agreement), much more than the USA.
Commodity price trends and changes in Colombian access to consumer credit (for Chinese knickknacks) are probably bigger factors in this chart than trade agreements.