Generally speaking, no. California law defines a work week as starting with the time you are scheduled to begin work in a week (for most people, 9am Monday) and ending at the same time a week later. In California, overtime pay is required if an employee works more than 8 hours in a day (1.5 times the hourly rate from 8-12 hours, then 2 times hourly rate for hours over 12), or more than 40 hours in a week. In California, even if you work less than 40 hours in a week, if you work more than 8 hours in a single day, (with certain exceptions, that probably don't apply to you) you are entitled to overtime pay.
The fact that you are paid every two weeks or twice a month or monthly doesn't change the overtime requirements. And, it doesn't matter whether you are an "hourly" employee or a "salaried" employee, the same rules apply as long as you are not classified as an "exempt" employee.
Also, generally speaking, California law does not permit employees to waive these requirements, so employers can not require you to agree not to be paid overtime.
If your employer is based in another state, they may not be familiar with California employment laws (which is more strict than laws in other states), but they are nevertheless required to abide by them if you work here.
If you feel you have not been paid properly for your overtime, you may make a complaint with the Labor Commissioner (there is information on how to do this at the California state website) who will collect the wages for you. You may be entitled to go back to previous pay periods to collect unpaid overtime, as well.
