AN INSTRUCTOR AND HIS STUDENT TAXIING A C152 AT MRY FAILED TO FOLLOW ATC INSTRUCTIONS RESULTING IN A RWY INCURSION.

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AFTER START UP I CALLED GND CTLR. I WAS CLRED TO TAXI TO RWY 28L AT TXWY L; I PROCEEDED TO DO SO. (THE WORDS 'VIA BRAVO TXWY' WERE NOT USED. THE GND CTLRS OMIT THIS PHRASE ABOUT 50% OF THE TIME.) WHILE ENRTE TO TXWY L INTXN I WAS TUNED TO GND FREQ 121.9. I COULD HEAR THE CTLR GIVING INSTRUCTIONS TO OTHER ACFT SUCH AS 'ENTER R BASE; CLRED FOR LNDG RWY 28L' AND WAS AWARE THAT ONE PERSON WAS ACTING AS GND CTLR AND AS THE LCL AIR CTLR. I COMPLETED THE RUN-UP AT L INTXN; BUT BEFORE I COULD CHANGE TO TWR FREQ; THE GND CTLR CAME UP WITH THE FOLLOWING DIRECTIONS. 'THE WIND JUST SHIFTED AROUND TO 070 KTS; WOULD YOU MIND SHIFTING AROUND TO 010 DEGS L FOR TKOF?' I REPLIED THAT THAT WOULD BE ALL RIGHT. I AM NOT CERTAIN I REMEMBER HIS NEXT XMISSION EXACTLY; BUT TO THE BEST OF MY BELIEF HE CAME BACK WITH 'OK; TAXI BACK ON RWY 10L FOR TKOF.' I AM SURE THE CTLR DID NOT SAY 'VIA TXWY B.' THE CTLR MAY HAVE SAID 'TAXI BACK TO RWY 10L FOR TKOF.' WHILE GOING DOWN TOWARD RWY 10L I RECALL THINKING IT WAS A LITTLE STRANGE HAVING A GND CTLR MOVE ME OUT ON A RWY; BUT AT THE SAME TIME I NOTICED THAT AN ACFT HAD JUST LANDED ON RWY 10R AND THAT THERE WAS ANOTHER ACFT ON A VERY SHORT FINAL FOR RWY 28L. UPON ARR AT RWY 10L I SWITCHED TO TWR FREQ AND REQUESTED CLRNC FOR TKOF. I WAS TOLD TO TAXI CLR OFF THE RWY. I DID SO. ABOUT 1 MIN LATER I WAS CLRED FOR TKOF. AS OF NOW I AM NOT SURE IF I WAS IN ERROR OR NOT AND I AM NOT GOING TO ASK MONTEREY TWR IF I WAS.