Well from my experience, it's not normal. I have basically run the same apps/tweaks I always have on Cydia on all my iPhones and never had the problem until my new iPhone 4 came along. I figure restore and rejb bc of the new fw release anyway and it went away. I dealt with it for a couple months trying to delete Cydia things and whatnot but it never worked. I could be wrong, but to be totally honest I think a restore and rejb is in order.