Like everything in life, there is a continuum from those who are lightly affected to those that are heavily affected.
With that said, you are very new to Paleo and have only been doing it a week. That is NOT enough time. You should go 3-4 weeks doing strict Paleo/Primal and then try having a big bowl of cereal and see how you feel.
Also, regardless of how you feel, the internal processes from that much sugar and crap (yes, Cin. Toast Crunch is PURE crap) is just not good for you.