It's completely random. The same code is used across games and apps when random numbers are required. People perceive patterns in small samples, but expanded over a very large sample, the rolls even out. I built and administer a large application at my company that has a few random number generators and I always get these types of complaints. However, I can prove that over a year, the numbers are indeed random and evenly distributed.
It's the same thing as playing black/red in Vegas. People think that just because black came up 17 times in a row that red has a higher probability of coming up next, but in reality, the odds are exactly the same every single time. Over time, they come up the same number of times.