Apparently it's been noted before by the MSM:
Obama, too?
One expects a certain amount of refunds - they're setting up for a relatively brief period of time, probably pulling in money/donations from multiple locations using volunteers. Stuff gets misplaced.
Now, in order to determine the scope of the problem, I'd want to see how much a few Republicans like Bush had to refund, and how their refund rate (% of transactions and money reversed) compares to say, charities and commercial businesses like Walmart.
Knowing that having to refund money is a thing for nearly anybody taking money (including criminals when they're forced to pay restitution), the question becomes, was the amount reasonable?
Considering that in 2012 Obama broke
$1B, a refund rate of less than 0.1% isn't something that I feel we can legitimately criticize him for.
And that's before you get into things like them deciding they don't want donations from 'politically negative' sources.