Don't worry about it. You knew it was safe to take. You had been prescribed that med in that dosage before. No biggie. I was given valium and given such a low dosage that it didn't really do anything. The second time I took it I waited a couple hours or so and then took a second. It worked and I told my pdoc about it too. He told me to go ahead and take two if I need it.
Not sleeping could be more dangerous than playing around with meds like what you just did.