I've experienced a "partial FR" when my CL was 12K and I called in to increase it to 36K, this was in the evening and they told me that a "certain department" was going to make the decision. Then about a week later I got a letter stating that in order for me to qualify for the CL increase, they would need to review my finances... along with all the FR papers and forms. All along my account was active at 12K CL.
Ignored the letter, and about a year later called in and they increased me on the spot to 28K and have since spent more than that amount (never exceeding 14k at once though).
Now I'm reading that over 24,999 it's a trigger, but if I call them to reduce it, wouldn't that trigger as well?