Does age matter to get a job/postdoc?
In principle, age discrimination is illegal in the US and various other countries in the world.

In practice, there are a lot of apparently legal ways to get around age discrimination (e.g. discriminating based on experience, work history) and I have heard of first-hand accounts of supposedly illegal discrimination at various institutions throughout the world.  There are a number of employment lawyers who go around arguing these kinds of cases.

However, at least in the US, being good and well-known is an inoculation against much of this discrimination.  Ultimately, if you are successful and active, at any age, you will be hirable.