mongo primary is showing behind the primary?
I don't know that I see a problem.  It says right in the second line shown that the source data is "source: xxxxxx:27017" and if you look further down, in the status results, that server is actually the secondary.  So the way I read this (and let me know if I am wrong) you are submitting the command on the Primary, but it is actually querying the secondary and saying it is over 7 hours behind the Primary.  Then you do a status and it shows the replicaSet with an optTimeDate of the same time difference.  

If I were to make a guess, (and this is only a guess) I would say that one of the two machines is time-sync'd via ntp but the other is not (and the arbitrator appears to match the primary, so it is more likely the one that is time-sync'd meaning your secondary is running slow).