It's not a big deal for me. I seldom use the cover unless traveling and want to stuff it into a suitcase or carry-on bag. In addition, when I hold the power switch to the right for about 5 seconds, it will flash green LED and the screen will blank to white. I then put it into the cover. When I remove it, prior to turning it on, it takes the same length of time (about 2 seconds) to turn back on to my last page as it does to turn it on from sleep mode. It does not reboot from scratch. The only 'hassle' is waiting the 5 seconds to turn it off.
Return the K3 and/or the cover if you want. I'll keep mine, thank you. If Amazon comes up with a 'solution' to such a minor 'problem', I'll let them send me a new K3 or cover, but I won't be without either one in the meantime. A cover without the security of the hooks is next to useless unless the K3 can be secured inside in some other manner.