I'm not expert, but from what I read, yes it could be. It could also be caused from stress. And there are other things too it could be. If you can, I would talk to your doctor about it. They could ask questions that will help determine if it is or not.
I am also 48. I didn't have a period from Oct 2010 to Aug 2011. I have been having very bad night sweats, drenching in fact - my night clothes can be wrung out. I just assumed I am going through the menopause but a friend said I should see a doctor. I don't however want to be one of the "worried well". Does anyone have any good advice for me?