I suspect that this is a common phenomenon. I used to be good at maths, damnit. I've just realised I can't remember any of it, after a couple of years of being out of college.
Someone should publish a book for people who had a maths-oriented education and then replaced all that information with crap about databases over a couple of years. A sort of catch-up. I want to be able to deal with things like moments and integration and so forth again!