er, sixteen years old is the age of consent in many places, I don't think there's anything "creepy" about a relationship between a 16-year-old and a twenty-year-old, no matter the genders of either of the ages.
Right, we don't know exactly what the laws are regarding this matter.
On an amusing note, it could have been "worse." According to Avery Brooks, Mardah was originally supposed to be played by the even-older Chase Masterson. Chase was vetoed strictly because of the combination of the age gap and her attractiveness.
Which would have meant, of course, that Jake would be living the dream of any teenage boy (certainly my dream at the time).