The API is returning a next episode link that points to a episode that aired yesterday. For example:
http://api.tvmaze.com/singlesearch/shows?q=challen...
Has "nextepisode":{"href":"http://api.tvmaze.com/episodes/541987"} and that episode aired YESTERDAY.
(This has happened before: http://www.tvmaze.com/threads/352/next-episode-poi... )