just a guess-- when a company sells stock, the underwriter is often granted the right to sell more stock than the posted offering, thus setting up an automatic short. The underwriter is further granted the right to buy additional stock from the company to cover any shortfall. This is known as a "Green Shoe" after the the company where the mechanism was first employed (the Green Shoe Company). By doing this, the underwriter can effectively create excess demand for a stock offering, thus stabilizing the stock price immediately after the offering closes. Again, just guessing, perhaps the short position was measured immediately after the equity offering.
I don't normally follow short positions but perhaps it's because of the increased shares. I'd check the percentage of short shares compared to last month. It may tell a different story. Just guessing. I'd also say with all the positive news and stock's price moving upwards shorts MUST think this can't go on forever. However, we've now got 13 days of positive stock movement. It is remarkable.
Also, the shorts may suspect additional stock offerings which could temporarily weaken the stock. Given their prior use of funds, I wouldn't worry too much about additional stock offerings unless something changes. But I do hope they will be able to finance some of their dealings withe the MSRs.