It depends. Some states are called 40hour a week states, and some are 8hrs a day states. In addition, the federal laws regarding overtime pay have recently changed, creating quite a stir to hourly blue collar workers.
For example, if you work in a 40hr week state, but the 41st hour was past the end of the work week, then no you may not be entitled to overtime, This is a very simple explanation of the new rules. What this means is: Lets say your pay period started on Sunday, and ended on Saturday. You worked 40hrs, Sunday through Sat, but you were scheduled to work on Sunday 4 hrs. To you, you worked 44 hrs that week, but under the law, you only worked 40hrs during the pay period, and 4 hrs at the start of the next pay period.
In an 8 hr a day state, you would be entitled to get overtime pay for anything worked over 8 hrs per day, not for 40 hrs per week. For example, If you worked 7 hrs a day for 6 days that equals 42 hours, but not one of the days did you work over 8, which means no overtime for the 2hrs worked in excess of the 40hrs. This can also incorporate the same previous example of pay period as well.
What you need to understand is the recent changes, about 2yrs ago, only affect going forward, not previous to the changes. There are other factors as well relating to overtime pay. For example the number of employees. If under 15, AND they do not receive interstate goods, then they may not be required to pay overtime. In today's business world the part about interstate goods really is out-dated part of the rules, but there are some small and local business that sell things that do not fall under the Interstate commerce clause of the labor laws.
Before you raise hell, be sure you understand your individual states overtime laws and that your position/company do not fall under the new federal guidlines.