Game Mechanics: Disease icon acting odd

[Rasah]

I zoned into Lake Rathtear from South Karana, and engaged 2 undead. I was diseased, so I cast Cure Disease and the icon went away.

Then I zoned back into South Karana, and the icon was back. I cast cure disease again, and it went away again.

About 10 minutes later, I got a message saying the disease had broke, or whatever.

Seems to me that the icon shouldn't go away unless the disease is actually cured.