While this is not normal, it is not necessarily cause for concern yet. I would inspect the cooler closely if you can, and check to make sure there are no wires or anything that could be making contact with the fan. A couple things to try to see if you can pinpoint where the noise is coming from, is adjust the fan speed manually with a monitoring program until you hear the ticking, and then gently press on the shroud, to see if the noise stops. Next gently press on the middle of one of the fans until it stops spinning, and then release, and repeat with the other if you have a dual fan card.
 
Also if it is only happening at certain RPMs, you can set a custom fan curve to have it go above or below those levels.