Your pH was fine, and it wont be correct when you are cycling a tank anyways. Those pH buffers that they sell you are pretty much junk, they rapidly change the pH (which is bad for your livestock) and then it just goes back to where it was over the course of a few hours.
Plus, the pH will naturally change over the course of the day. As algae in the tank performs photosynthesis, they take up the CO2 in the water which decouples from water molecules (together the interact to form carbonic acid) which cause the pH to rise. The pH will naturally rise over the course of the day being highest right before the lights go off. Then when the lights go off, the CO2 is no longer being consumed so it stays in the water and interacts with the water to form carbonic acid, lowering the pH.
So its important to test the pH at the same time every day.