Just going to quote myself from the last two times this topic arouse.
This is a huge misconception about the middle ages. Everyone thinks that the average person only lived to be about 30 or so and then they would die out. However, the true of the matter is that if you lived to be 21 years old, your life expectancy is actually about another 43 years, which would have them dying at age 64. So, seeing a 60 year old (woman especially) was very, very common.
http://apps.business.ualberta.ca/rfield/lifeexpectancy.htm