If you have "fold waves" I'd say you're more than safe, Ben. And to be sure, so as not to create any undue anxiety, all I am stating is that the one I received is not authentic and, usually, that indicates others.
Consider, we're talking about a 22 year old film that won numerous awards including the Mainichi Film Award, Kinema Junpo Award and Animage Grand Prix best film '88; one of the most quintessential, awarded, most regarded anime film's to date and 22 years later the B1, a relatively rare format, can be had readily on eBay and has appeared a peak number of times at auction in 2008 and 2009 alone. I do not believe it's deliberate on part of auctioneers.
With the poster in hand it could not be more apparent. I have others of that region from early and mid 80s and, needless to say, my other B1 from that decade are without lint, dust, dirt and pubic hair. The Totoro B1, in contrast, shows a scattering of small dust, lint and dirt particles and the over all color is muted. At first glance the dust appears actual, when you attempt to wipe them away it's clear they're scanned physical artifacts trapped between the original poster and the glass of the flatbed. I'll take close ups of the issue and post them up at noon tomorrow for you all to form your own conclusions.