I assume you deposited the RMD into the Vanguard Fund when you originally took it out.
When you went to pay it back - you withdrew the original amount from the Vanguard account. When you withdrew the amount from Vanguard I am guessing you did not specify the "lots" and based on the Date acquired in your note - the lots were taken from 9/17/2013. I also would assume the Cost Basis of the shares taken were less than the sale price - therefore, you have to pay capital gains on the withdrawal. If you had selected the lots - based on cost closest to the sale price, the gain would have been less. If my assumptions are correct there is nothing you can do but pay the capital gains on the $893. I have no clue if you can change the lot assignment and even if you could my guess is that it would not be corrected until after May 15th.
