Someone correct me if I'm wrong but no you do not have to relock your phone to flash the shipped rom. I like to flash back to the stock rom every now and again in hopes that it irons out some bugs that may have been worked into my phone over several custom rom flashes, and I haven't had to relock my phone so yeah... flash stock, hard reset, then flash the new rom, hard reset and away you go with a much improved touch pro
