ACR MLG MAY HAVE CROSSED AN ACTIVE RWY WITHOUT CLRNC.

Narrative

UPON LNDG; TWR XMITTED DURING ROLLOUT TO ADVISE US OF TURNOFF; INSTRUCTIONS FROM RWY 11. I'D BET MY PAYCHK THAT TWR'S DIRECTIONS WERE FOR A L TURN AND TAXI TO PARKING. AS I COMPLETED THE AFTER LNDG CHKLIST WITH NO URGENCY IN MIND SINCE I HAD HEARD CLRNC TO PARKING; I CHANGED THE RADIO FREQ TO GND AND WAS ADVISED TO RETURN TO TWR FOR FURTHER INSTRUCTIONS. TWR ADVISED A TELEPHONE NUMBER TO CALL. IT SEEMS THE TWR CTLR FELT WE CROSSED AN ACTIVE RWY WITHOUT CLRNC. THE CAPT AND I DISCUSSED TAXI CLRNC WHILE EXITING THE RWY AND AGREED THAT WE WERE CLRED TO TAXI TO THE RAMP. WE RECEIVED NO 'HOLD SHORT' CLRNC. I DID NOT HEAR THE CAPT'S PHONE CONVERSATION WITH THE CTLR; BUT I UNDERSTAND HIS CONCERN. THERE WAS NO TFC (OTHER THAN WE) ON THE ARPT AT THAT TIME. A LIGHT ACFT LANDED ON RWY 11 ABOUT 5 MINS BEHIND US. THERE WAS NEVER ANY POTENTIAL CONFLICT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR HAD NEVER FLOWN WITH HIS CAPT BEFORE OR SINCE; AND HAD NEVER BEEN INTO MSO BEFORE OR SINCE. THE RPTR DOES NOT KNOW IF THE TWR GAVE OR DID NOT GIVE A FREQ CHANGE. NONE WAS ACKNOWLEDGED. THERE WAS ONLY ONE OTHER ACFT IN OP WHILE THIS WAS GOING ON. THE CAPT WAS PROPERLY CONTRITE WHEN TALKING TO THE TWR. APPARENTLY THE TWR CTLR WANTED THE CAPT TO SET UP A PROGRAM AT THE CAPT'S HOME BASE TO MAKE OTHER PLTS AWARE OF THE GND TFC SIT AT MSO. THE RPTR THOUGHT THAT THE CAPT WAS BEING 'SPOKEN DOWN TO' BY THE TWR CTLR. THE RPTR WANTS THE ASRS TO KNOW THAT HE IS A RETIRED O-6 FROM THE USAF. THE RPTR HAS NOT HEARD FROM THE FAA ON THIS MATTER.