The midfielder is back at Deepdale undergoing treatment having been ruled out for over a month with the hamstring injury which forced him off in the first half of Saturday's 4-1 defeat at Rotherham.
Mousinho was due to remain at Priestfield until January having made six appearances since his arrival at the League One club at the start of November.
His injury and subsequent departure comes shortly after Elliott Hewitt was also forced to return to parent club Ipswich due to a fractured ankle.
The full-back missed Saturday's encounter at the New York Stadium altogether and also faces around a month on the sidelines.
Elliott had only joined the Gills in mid-November and was due to remain with the Kent outfit for a month.