A fetish is typically defined as getting sexual satisfaction from something that is not normally considered "sexual"; so by definition, I feel that a fixation/appreciate of feet could technically be defined as a fetish.
Fetish: an object or bodily part whose real or fantasized presence is psychologically necessary for sexual gratification and that is an object of fixation to the extent that it may interfere with complete sexual expression.
I don't see anything wrong with that, though.