I was under the impression it was 20, not 15. Though wow.com does say 15. I'll change it and see how it works.
I tested it a bit before I posted this, and I found that 20 seconds is definitely too long. It drifted somewhere around 15-16 secs (couple times I landed a cyclone after 16 seconds that got DR, don't know if it was lag or something else), and I've seen most websites report it as 15.
Anyway, really awesome job on the addon, I've replaced quite a coupole old addons with this gem, keep up the good work!