Roth 401k Rollover to my Roth IRA

I am trying to roll over my Roth 401k to my existing Roth IRA, but my former employer is telling me that they need to to transfer any gains in my Roth 401k to my Pre-Tax 401k because of the "5 year rule".  I thought that the 5 year rule would apply to distributions, but are they correct in applying it to a rollover transaction?