It happened to me during the OM $10 off few weeks ago... in my case the first day the supervisor asked how much are you buying because we have to file a report above certain limit (refused to tell me the limit on that day),ended up not filing the report because it was less than $2000 I believe...But the next day went for more....about 6 or 7 $200 cards...the cashier calls the same supervisor who talked to me the day before and sates that since I'am about to buy more than $2000 worth of GC (CUMULATIVE) the report needs to be filed so I refused to fill it out and just walked out...
This could be store specific (or manager/supervisor) YMMV though..