I think what your hearing (I hear it too, and it's damned annoying), is a distortion created somewhere in the editing process by the use of a time-compression application, which they use to stretch or shrink sound samples so they match up in length(and so a piece of music matches up with a certain number of frames of film)

This is the sort of thing they use in rap/hip-hop recordings to make bits of speech match the beat. It is the audio equivalent of "justify" button in the word processor that lines up the ends of all the sentences on a page by either adding to or subtracting from the spaces between words to create a nice clean block effect.

The thing is that, depending on how well or badly the editing is done, some to all of us can hear the places it was squeezed to fit.