She got off on a sour foot

This is a blend of “strike a sour note” (signify something unpleasant) and “off on the wrong foot” (starting something, like friendship, with negative factors, both indicating something unpleasant or, as my “ol pal” says, leaves someone with a bad taste in his/her mouth.  Perhaps the speaker was referring to “the shoe pinches” malaphor posted a few days ago.  My guess is if a shoe pinches it will result in a sour foot.