Pump running at a higher pitch

I just opened my pool and everything is working well. I am concerned, though, that the pump is 'whining', running at a noticibly higher pitch. Before closing last year, it was humming. Should I open up the pump to look for any foreign substance or is this just a sign of age and I should start looking for a replacement? It's a Hayward 1 1/2 HP Super Pump. Not sure how old it is since I got it with the house 2 1/2 years ago.

You may have some debris stuck in the impeller of the pump. separate the pump from the housing that conatins the strainer basket via either bolts or a clamp(depending on the pump) exposing the impeller. You can remove the debris with your fingers or a needle nose pliars. Just make sure the power is off.