I have assumed there was some short covering late Aug/early Sept and that helped push the shares over 70. Maybe that happened, but if so, new shorts entered
Looking at the NASDAQ short interest site, short interest has increased significantly since 8/15:
8/15 4.054 M
8/31 4.097 M (this is after the nice Q results were released)
9/14 3.903 M
9/28 4.476 M
10/15 5.111 M
10/31 5.525 M
Yup, from 8/15 - 10/31, short interest has increased by 36%!
The shares aren't cheap right now; what will prompt shorts to cover? Of course, a higher share price attracts new shorts.