RMAN duplicate takes a long time when restoring one particular data file

 I do a daily duplicate from a backup for a reporting server.  According to the alert log, most files take 2-3 minutes to restore and a couple up to 20 minutes.  There is one file, which is the largest data file, but only by 200 mg, that consistently takes over an hour to restore.  LOGIC_IXnn files are all between 23.5 and 24 gig with 01 being the largest.  Here is a section of the alert log:

Full restore complete of datafile 32 to datafile copy \ORACLE\DATA\RPT01\LOGIC_IX04.DB. Elapsed time: 2:17:06 
checkpoint is 7615307472
Mon Jan 27 06:54:42 2014
Full restore complete of datafile 31 to datafile copy