Share 'tempering problems'

I am molding bars of dark chocolate and recently have starting having strange spots on the bars in only one place on each bar, but it moves..  its looks like cacao butter film.  I am baffled as to what might be causing this.  I wonder if its the temperature in my shop?  I put all the bars on shelves to cool.  I used to put them directly into the freezer and had no troubles then,but I thought that…