Examining your hands is actually another RC. Do you remember what your hands looked like? If they were different from normal, which they usually are in a dream, then it may have surprised you a little bit causing for your dream to fade. Rubbing your hands together is a form of stabalization but all you really need to do is immerse yourself in your surroundings. Like practicing ADA inside the dream. Rubbing your hands is just a method of doing this without putting too much thought into it.

Of course, the dream could've just been over by then. All dreams have to end at one points or another so it's not unlikely that you became lucid at the end of one. It's happened to me several times and, though it's annoying, it's a perfect opportunity to try a DEILD. It's actually a great method to get good at since once you get better you can recognize when regular dreams are ending, become lucid for a split second, and then remember to remain still and preform a DEILD.

Hope this helps