i'm feeling particularly paranoid this evening ...

I have a question for people who have maintained aquariums for a really really really long time. How long have you had an aquarium running before you notice problems from wear and tear, especially along the seals?
I've had my 40 gallon glass (Perfecto) running for 10 years, and it's been great. But how long can those seals last before it starts to weaken? Should i think about replacing it?
If i have to replace it, should i get an acrylic tank instead of glass?
thanks!
shireen