I hear it all the time: My new massage table isn't lying flat! It didn't completely unfold. Is it defective? In a word: No. Well, at least not most of the time. There are, of course, incidents of defective tables out there, but I would argue that in almost all cases, a new table lifting slightly in the center is a result of one of two things: improper opening or a twisted cable.
Most tables have been in their folded position for quite some time before you unpack and open them. It shouldn't be completely surprising, then, that they might have a propensity to stay in that position. That is why opening them correctly is of monumental importance. When you unpack your new table, open it up and flatten it out by pressing down on the center while you pull out the end of the frame. If it still isn't completely flat, you likely have a twisted cable. Diagnosing a twisted cable is simple: Run your fingers slowly along the length of the cables until you find the twisted piece. You'll know it when you find it. Luckily, a twisted cable is an easy fix and it's even one you can do yourself.
In short, if your new massage table isn't lying flat, don't panic. It's likely one of the two aforementioned issues and these, luckily, can be fixed in a jiff.