Clinically low isn't low until your under 250-300 range depending on the lab test. Now for your age you should be in the 6-800 range. But you did it at 9pm at night where its going to be lowest. Other things can affect the level such as alcohol, diet, overweight, sleep, other medicines or drugs.
Personally if your in that range at night your probably going to be in the 600s if not more after a some good sleep in the morning. If your concerned with low T, at your level your better off working on diet, exercise, sleep before taking on TRT>
I would also suggest checking your thyroid along with prolactin.