Normal sound when turning off sounds sick

I'm aware that when I turn my 2007 Prius off, it is normal to make sounds from the engine compartment.

What troubles me, is that these sounds are now intermittent, leading me to think that something is failing. Sometimes they will be normal, while other times, it will make the normal sound for a second or two, then stop, then start, then stop, and in general sound like it is struggling to do what it used to do with ease.

I'm guessing this is the Coolant Heat Storage Water Pump. Is this a common problem to have it fail, or change its sounds over the life of the car?

I'm at the dealership now, having a recall done on the car, but had a hard time explaining this problem to them...