Is it normal to forget the specific details of a technical literature after few weeks or months?

Do you use the information in the literature regularly? if not, then it doesn't seem odd. As long as you remember the basic info - and know where to get the specific details you're good.

I work with legislation with many many many movable parts. When I was first trained to use it, my trainer said the most important thing to know was how to find the references, not to memorize the references.