Rapid changes in short positions can mean:

1)      insider information is in play; falling short volume would be favorable to stock holders.

2)      the speculative mood has changed, one way or the other. Speculative mood is generally considered a counter indicator; so falling short sales would not be favorable to us stock holders.   

Although the percentage change was high (- 49%), the actual short interest has been and remains low, less than a tenth of a percent of  the shares outstanding. This could mean that the rapid short interest change is insignificant - just like large stock price changes can be insignificant when trading volume is very low.