mobile

Hi all, I have a strange problem that started about half hour ago. Basically I've recorded some gameplay videos on my ps4, I just connected my z2 to ps4 in mtp mode, copied a couple of videos from ps4 to usb storage (my phone) and since doing that my phone keeps unmounting my sd card, then it mounts, then unmount and just keeps repeating that cycle.
This isn't the first time I've copied videos from ps4 to my phone but it is the first time I've experienced this problem, any ideas? Tried rebooting, didn't solve it, also had my notification list fill up telling me "rental expired" on all vids from the ps4....... Help