If you used mold release, it is possible. The best thing you can do is use very warm soapy (Dawn or Cascade Gel). Then clean with Rubbing Alcohol and allow it to dry. A primer coat painted on prior to airbrushing or detailed painting helps adhesion as well. The Universal Mold Release can usually be painted over if used as a mold release if used in moderation and not sprayed heavily. Paint adhesion is also best if applied soon after pouring while the resin is still curing. Waiting days, weeks, or even months, may require abraiding the surface, cleaning with a mild solvent, and thoroughly drying before painting.