Glucose test

So I was at my first prenatal appointment in my new hospital today at 26 weeks. I wasn't expecting to take a glucose test and was surprised that they wanted me to do the glucose test that appointment. In the morning around 8ish I ate lucky charms (running late and that's all we had for a quick breakfast) and then around 9:20am I ate a chocolate chip granola bar. I had my drink at 10:58am. Online it says not to go over 134. My results were at 136 so now I'm freaking out that I may have diabetes and I'm so horrible at eating super healthy. Could eating a sugary breakfast have caused me to go over some? I'm waiting for my doctor to order my 3 hour fasting test at the moment.