Contextual plasticity (CP) is a short-term adaptation effect in sound localization (Kopco et al., 2007). CP is exhibited by biases in localization of click stimuli in target-alone trials when, on interleaved contextual trials, a distractor-target click pair is presented. In previous CP studies, a gradual drift in localization responses towards the front was observed. The drift was not attributable to CP but can potentially confound its analysis. Here, we analyze several CP data sets with various distributions of contextual and target-alone stimuli in order to test whether the drift is related to asymmetry in the distribution of the stimuli relative to the subject's midline. The results show that the drift tends to have a steeper slope when the stimulus distribution mean is more lateral, confirming that it is likely related to the distribution asymmetry.