If the "transfer" was to an IRA account of the same type (traditional or Roth) at the brokerage, it is indeed a nonreportable transfer, neither a distribution nor a rollover.
If the money was moved to an account that was not an IRA or some other qualified retirement account, it was a distribution from the IRA at the credit union, not a transfer. In that case you must inform the credit union of their error in treating this as a transfer and they should provide you with a 2016 Form 1099-R reporting this distribution.
