Large SLV Deposit on January 16th (2013). Did JPM close a short position?

An interesting piece of analysis here from suggesting that JP Morgan may have closed a significant short position in SLV without affecting the SLV price:

Why Was 18.3Moz Deposited?

The obvious answer is "JPM opened a new warehouse!".

However, that does not answer the question, as only 10Moz went into their new warehouse.

The experts seem to agree that one of the most plausible explanations is that JPM closed out their short position in SLV. One or more people have 17,016,600 shares of SLV short (about 16,458,115oz) at last count (which could be a couple weeks old). It is believed that JPM is likely responsible for much or all of that short position. The unexplained addition of 17,410,210.4oz to SLV (remember, 967,881.6oz are considered a 'normal deposit') would cover the entire short position and then some. Or if another 967,881.6oz (1M shares) were a normal deposit, that would leave 16,442,329.4oz unaccounted for, almost exactly matching the short position.

Another possibility is that someone wanted to purchase about $500M of silver, using SLV, with minimal change to the price of silver. Since it would be cheaper to store $500M of silver directly in warehouses (rather than via SLV), such a buyer would likely be a mutual fund (or similar) that is allowed to invest in ETFs, but not in silver directly. However, this theory seems less plausible given that the silver was all deposited on the day that the new JPM SLV warehouse was introduced.