Because it shares its rakes with Howrah-Puri Jagannath Exp. Primary Maintenance of this train is done at Puri. That's why Gitanjali is an Ecor train.
In this same way,Chennai Egmore-Salem Exp is also an CR train though its home zone is more than 500 kms away because of its rake sharing with 12163/64 Dadar-Chennai Sf