By means of computer simulations of a coarse-grained DNA model we show that the DNA hairpin zippering dynamics is anomalous; i.e., the characteristic time scales nonlinearly with , the hairpin length, with . This is in sharp contrast to the prediction of the zipper model for which . We show that the anomalous dynamics originates from an increase in the friction during zippering due to the tension built in the closing strands. From a simple polymer model we get with being the Flory exponent, a result which is in agreement with the simulations. We discuss transition path times data where such effects should be detected.