AN ACR MLG MAY HAVE HAD A TRACK DEV; AND MAYBE THE AIRWAY ARCS IN THIS AREA.

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WE WERE ON A VECTOR FROM ZLA TO INTERCEPT J72 E OF PGS 076 DEG RADIAL. FO HAD FLOWN SLIGHTLY THROUGH J72 (1/8 DOT) WHICH I WAS WATCHING AND GETTING READY TO MENTION WHEN THE CTLR ASKED IF WE WERE TRACKING J72. I REPLIED THAT WE WERE INTERCEPTING AT WHICH POINT HE SAID WE WERE SUBSTANTIALLY N OF J72 AND GAVE US ANOTHER HDG BACK TO IT. THIS CONCERNED ME BECAUSE WE WERE SHOWING SUCH A SLIGHT DEV FROM ON COURSE; SO WHEN ABLE; I QUESTIONED THE CTLR ABOUT IT. I BEGAN BY ASKING HIM IF THERE WAS A HISTORY OF TRACKING PROBS ON J72 IN OUR AREA. HE REPLIED THAT INDEED THERE WAS COMMONLY WHAT HE TERMED AN 'ARC' OR 'ARCING' PROB THERE; BUT FURTHER CONVERSATION REVEALED THAT HE SHOWED US BEYOND THE 'ARC' (WE WERE THE 1/8 DOT I MENTIONED EARLIER) AND I GOT THE IDEA THAT HE THOUGHT WE WERE PLANNING TO INTERCEPT J128 (PGS 059 DEG RADIAL) IN ERROR. I MUST EMPHASIZE HERE THAT THERE WAS NO ERROR MADE BY THE CREW. WE HAD THE CORRECT FREQ AND RADIAL TUNED AND SET WITH NORMAL CDI INDICATIONS FOR THE BRACKETING DOWN PROCESS OF INTERCEPTING A RADIAL. BUT THE 'ARCING' OF THIS SECTION OF J72 CAUSED THE CTLR TO MISUNDERSTAND OUR INTENTIONS. THE 'ARCING' PROB J72 SHOULD BE LOOKED INTO AS IT MIGHT CONCEIVABLY CAUSE A LOSS OF SEPARATION.