Snape 'always' loved Lily Potter - his statement has nothing to do with Harry himself

There are many moments in the Harry Potter books where Snape expresses resentment towards Harry as a character due to his physical similarity to his father. Dumbledore asking 'after all this time?' is a result of his surprise that Snape's patronus is still a doe - indicating that Snape still loves Lily. His response of 'always' therefore shows that his love for Lily is eternal, not that he has been hiding his love for Harry.