How old are the impeller, thermostat, poppet valve? The cooling system may be marginal and it's enough to cause the overheat condition in warm water. Might be time for a little servicing.
It's a good idea to replace the impeller every year on those Triples, anyway. Loss of an impeller is almost guaranteed to result in a cracked block, so the $20 or so impeller is definitely cheap insurance!
When you're in there, check the pump stainless "cup" insert and also the pump plate. If they have any scoring or wear, renew them. Worn parts will most certainly reduce pumping efficiency.
Last thought, when you get an alarm, is the powerhead actually getting hot? Feel the exhaust manifold cover, it should never get much warmer than the cooling water's temp. If it's hot as a pistol, then the engine is actually overheating. Make sure you have a 125 degree, and no hotter, thermostat. If the motor shows no signs of being hot when the temp alarm goes off, you may have a faulty temperature sensor. Your manual will have the testing procedure for the sensor.
HTH.......ed
