Can be a number of things.
Sounds like oil residue on plastic. Did you soak the sprues in mild detergent?
What primer did you use?
What thinner did you use? (assuming you used thinner) I recommend using Mission Model brand thinner.
Did you let primer dry completely before handling and/or applying paint?
Did you let paint dry completely between coats?
Did you spray too close to the kit?
Lacquer clearcoat would have held up better when using panel accent liner. Acrylic clearcoat on acrylic paint sounds more the problem why the paint came off.