Low Coolant

[marq]

New member, just picked up a pair of 08's for the family.  After about 30 min of riding one of the bikes high temp lights came on.  Next day found the radiator low of coolant yet reservoir was full, all holes seemed ok, nothing plugged.  Re-filled and will keep close eye on over the next few days.

Any know issues?  I'm assuming a possible defective cap!