No, the paper is not flimsy at all. It's in keeping with most of the posters produced at this time. I know it's a pain but I would send it back and get a refund. If nothing else you will have piece of mind.
Also in my very limited collecting of new posters I have some from the early 90's and they are on the same glossy paper. I'm sure Quadbod will confirm this also.
Broadly speaking, yes - that's right - but we know even less about 'new' posters (that's anything since 1990!). Best way is to post images and dimensions, etc and make a direct comparison with a known reference example.
Going back to the safer territory of older posters, I can point out that occasionally different paper types do appear, even in apparently identical print-runs of the same title. So - as with the 'check for fuzzy print' rule - every pointer should be taken into consideration without making an absolute 'right or wrong' decision based on one doubtful element.
At a recent fair, one customer was examining the NSS text at the bottom left corner of one of our STAR WARS quads and was asking reasonable questions about the slightly blurry printing. We know the poster is absolutely OK but his questions were obviously based on sound advice. Similarly, the old maxim of 'no printer's credit means re-release' has often been the cause of unfounded concerns about the originality of a poster. It's always advisable to take the wider view and check as many factors as possible - just in case! If, after checking every aspect, there is still doubt, then, as Paul says, take whatever steps are necessary to give you absolute peace of mind.
Let us know what you decide!
Best wishes,
Terry -
www.quadbod.co.uk