FLC DEV IN FREQ CHANGE MADE WITHOUT AUTHORIZATION FROM CTLR.

Narrative

THE ATIS INFO WE RECEIVED STATED DEPARTING RWY 4 -- HOLD SHORT LINE #1 IN USE; LNDG RWY 13. NEARING THE RWY (ABOUT #3 FOR TKOF) WE HEARD AN ACFT ON GND FREQ WHO HAD JUST LANDED STATE; 'THE BRAKING ACTION WAS POOR TRANSITIONING TO NIL AT THE END OF THEIR ROLLOUT ON RWY 13.' SITTING #3 FOR DEP; STILL ON GND FREQ; WE ASKED IF THEY WANTED US TO CONTACT TWR. GND CTL SAID NO; NOT YET. A MIN OR 2 LATER; THE ACFT IN FRONT OF US STARTED TO TAXI ONTO THE RWY FOR DEP. NOT WANTING TO MISS OUR SOON EXPECTED TAXI INTO POS CLRNC FOR DEP FROM TWR; WE FLIPPED THE FREQ TO TWR FREQ. FOLLOWING BEHIND THE LEADING ACFT; WE STARTED TO CONTINUE OUR TAXI UP TO THE #1 HOLD SHORT LINE. RIGHT AFTER WE PASSED THE #2 HOLD SHORT LINE; TWR CALLED US AND TOLD US TO HOLD SHORT OF HOLD LINE #2. MY FO RESPONDED 'ROGER;' BUT SINCE WE WERE ALREADY PAST IT; I TOLD HIM TO TELL TWR WE WERE ALREADY PAST LINE #2. TWR RESPONDED; 'OH!' APPARENTLY; WHEN THE BRAKING ACTION ON RWY 13 WAS RPTED 'POOR TO NIL;' THEY CLOSED RWY 13 AND CHANGED OPS TO ALSO LAND ON RWY 4. WE WERE NEVER NOTIFIED OF THE CHANGE IN HOLD SHORT LINES AND HOLD LINE #2 IS FOR THE ILS 4 CRITICAL AREA PROTECTION. WE WERE IN IT. WITH AN ACFT ALREADY ON FINAL; THEY RUSHED US OUT FOR TKOF -- WHICH LEADS INTO ANOTHER NASA RPT TO FOLLOW. CONTRIBUTING FACTORS -- IT WAS SNOWING PRETTY GOOD AND WE WERE NEARING OUR HOLD OVER TIME. WE WANTED TO DEPART SOON. IN THE FUTURE; I'LL CONFIRM I CAN LEAVE THE FREQ BEFORE I FLIP THE SWITCH.