I've never put a pressure cooker in the dishwasher and would hesitate to do so. Thorough handwashing has always been sufficient for me. I would suggest that you check the vent hole(s) to be sure they are clear. You can use a small wire to thread through the hole to clear it if necessary. Another thing you can do to keep the gasket healthier is to store the pressure cooker with the gasket stretched around the outside of the bottom pan. This will keep the gasket from shrinking, although most of the newer ones are less likely to shrink because of the material of which they are made.
Other than the suggestions I've made, I don't think there are any other precautions you need to take. Just enjoy your pressure cooker. It is a wonderful kitchen tool.
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!