Hayward Super Pump question

Hi,

Seeing a thread about one of these pumps brought to mind an issue I'm having with mine. When it shuts off, occasionally it makes a noise like it is still running - kind of a 'whirring' sound of descending pitch until it finally stops. I've never had a pump do this before. It is only 3 years old and has always worked fine. Pressure, etc. is good, but it's just weird that it makes that noise - almost like the water pressure is forcing it to spin the other direction as soon as the filter shuts off (?) Any ideas? It also sounds just a bit louder when running then it did before.

Thanks,
Keith

If you have a lot of trapped air under pressure in the filter, that can sometimes cause a backflow after the pump stops and the air bubble expands....unlikely but possible. Question....do you see any water coming back out the skimmer when you kill the pump? If you're getting a reverse water flow you should see it there.
Al
Edit: Not sure but I don't think running water through a centrifugal pump backwards will spin the impeller.