He released his tax returns: http://money.cnn.com/2012/09/21/pf/taxes/romney-tax-return/index.html?hpt=hp_t3 Nothing shocking so far, except for how little he actually pays, and how much he gives to the LDS.
If he did, I'm sure you can cite the reference. Then perhaps you can take a stab at explaining why the rest of us have to file no later than April 15th, but he gets a 5+ month extension.
I'm sure you can cite Reid's exact statement while you're looking for this: Oh, right. You're too busy watching the clock to substantiate your claims.