I arrived in the states in July. I got admitted. Now I want to fly from NY to LA in Sept. I will have problems at entering again back to the country if my passport ( Hungarian ) is stamped till October?
When you take a domestic flight, there is no passport control at all. There will only be a security check where they check you have a valid ticket (and they will need your passport), but they don't care about the stamps or how long you stayed.
It is only when entering the US from another country that there will be real passport control, with your passport getting stamped