ACFT TAXIED TO GATE WITHOUT GND CTL CLRNC.

Narrative

LANDED ON RWY 31C. UPON CLRING RWY; TWR INSTRUCTED US TO CROSS RWY 31R AND CONTACT GND. ALL COCKPIT DUTIES COMPLETED NORMALLY AND ABOUT THE TIME WE WOULD CALL GND THE SO SAID; 'CLRED TO THE GATE' AFTER HAVING RPTED TO OUR OPS THAT WE WERE ON THE GND. UPON ARRIVING AT THE GATE; I NOTICED (WAS INFORMED BY FO) THAT WE WERE STILL ON TWR FREQ. SO WE DISCUSSED THE FACT THAT WE JUST TAXIED IN WITHOUT A CLRNC. WE WERE ON TWR FREQ THE ENTIRE TIME SO THEY COULD HAVE CONTACTED US IF THERE WAS A PROB. I WAS NOT BUSY AND WE WERE THE ONLY ACFT MOVING WITHIN EYE SHOT. WE DID NOT CROSS ANY ACTIVE RWYS AND CLRED BOTH DIRECTIONS EACH TIME WE CROSSED A RWY (RWY 4L&R). WE OFTEN GET CLRED TO THE RAMP BY TWR AND IT SEEMED NATURAL TO TAXI IN WITHOUT TALKING TO ANYONE. THE SO'S CHOICE OF WORDS WAS BAD BECAUSE IT LEFT THE IMPRESSION WE WERE CLRED BY TWR. I FLY INTO MDW ALL THE TIME AND TOOK THE NORMAL TAXI RTE TO THE GATE BECAUSE WE ARE NOT ALWAYS GIVEN SPECIFIC INSTRUCTIONS TO TAXI TO THE GATE/RAMP. IT WAS A VERY ODD SIT BECAUSE THE ENTIRE CREW WAS QUITE DILIGENT AND PROPER. OTHER THAN A HOPEFULLY INFREQUENT LAPSE INTO COMPLACENCY; I HAVE NO EXPLANATION ON WHY WE DID THIS. I GUESS IF A PERSON FLIES ENOUGH; THESE THINGS ARE BOUND TO HAPPEN EVEN THOUGH WE TRY OUR LEVEL BEST TO DO IT RIGHT ALL THE TIME.