From The Physics arXiv:
Last week, the world of science was ablaze with the news that astrophysicists had found the first evidence of ripples in spacetime from the instants after the Big Bang. The discovery of these gravitational waves would be big news by itself but there was another aspect to this work that was even more significant.
The work also found crucial evidence for a process known as inflation: that in the instants after the Big Bang the universe expanded explosively—by some 20 orders of magnitude in a fraction of a second—making it the size we see today.
But even before the sound of champagne corks popping has died down, theorists are beginning to question the new result. Everyone agrees that the data shows important evidence of gravitational waves. The question is whether these waves could have been created after inflation, rather than before it. If so, then they do not provide any evidence that the early universe expanded so quickly and the celebrations have been premature.