As mention has recently been made in the Seforim Blog of the Imrei Emes's missing library. I will try to summarize the little I know of it. (Hopefully some commentors can fill in the rest). Before WW2 the Imrei Emes took a large group of his Chassidim and buried his entire library in an unknown place some distance from Gur. The library contained many old and rare manuscripts and seforim as well as the Sefas Emes on the remaining sedarim of Shas (Zeraim, Nashim, Nezikin) and Imrei Emes's Chiddushim on all of Shas and on Chumash as well. After the war, it was found that most of those that had knew of the burial site had been muredered HY"D. Search parties sent out later on (after the Iron Curtain came down)with those few remaining survivors who had seen the burial proved unsuccesful.
According to a Gerrer Legend, the Imrei Emes had told his Chassidim -who were slow in printing out Sefas Emes Al HaShas- that if you don't hurry the Sefas Emes will take his chiddushim back.
It would appear that the Sefas Emes "took them back".