I received an additional 1099-R after I filed. It was a transfer of my 401K to my IRA. Do I need to amend my return even though I won't owe any taxes from this?

Yes, you should amend and include the 1099-R even if it makes no changes to your taxes. The IRS will match forms. 

However, there is no rush. The 1040X form will not be ready until mid-February. In the meantime, make no changes to your original return. This can really mess things up. 

The IRS amend form is not ready until mid-February. When it's ready, check the link below for directions to amending your return.

If you have already filed your return, you must wait until the return is accepted/rejected. If rejected, you can go ahead and add the 1099-R.

If you have already filed your return and it is accepted, wait until the original return is fully processed. If you had a refund/tax payment due wait until you receive the refund or the payment is processed.

https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed