I've read an article about the LSAT, printed in a law review, in which the author says that they showed a few LSAT questions to older law professors (who had not taken the modern LSAT), and many of them struggled with the questions.
There are some problems that you wouldn't expect to see in "modern" LSATs (the calendaring question from PT 7 comes to my mind), and some problems are rather unusual. I think that LR questions from June 2007 and onward are more difficult though.