Does the same for me too. If my iPad has been locked for a while and I come back and open my smart cover I will see any new text/imessages pop up...then after a few seconds of it being stuck it reboots itself into safe mode.
I really only Jailbroke the iPad for Bitesms. I have tried some other tweaks for it but nothing has really caught my eye. If Bite keeps giving me these problems I don't know if a JB iPad is for me. I know my iPhone 5 sure does love the JB though