An appeals panel has rejected a suburban man’s challenge to a sex offender law banning him from public parks.The 2nd District Appellate Court this week denied Marc Pepitone’s claims the offense is an unconstitutional ex post facto law because it was enacted 12 years after his conviction for sexually assaulting a child.Justice Susan Fayette Hutchinson authored a 10-page opinion Wednesday, writing laws are retroactive when they change consequences for actions that were concluded before the provisions are enacted. …