I had normetanephrine plasma free blood test drawn : result was (h) 0.92 should i be concerned?

When you hear hooves: In North America, usually it's a horse. Discuss this result with the Doctor who ordered the test. They will be best suited to interpret the value of this in the context of your individual case, and whether it's meaningful or not. Usually we use this test to rule out a rare "Zebra", pheochromocytoma, which almost never is the cause of the symptoms, often flushing, high BP and anxiety/palpitations.

Not yet, but...: Numbers are just numbers, without knowing the whole story. If this test result is slightly above the reference range, one's doctor will look at the whole picture to see if more testing is needed. More tests might be needed. A reference range is where 95% of normal people have results in, which means 5% of normal people have results outside the reference range. Hope to be one of those normals.

Probably not: It sounds like you were being screened for a pheochromocytoma, which can elevate that blood test. But pheo's usually cause HIGH blood pressure, not low, like you have. Your normetanephrine can also be intermittently elevated from stress, caffeine, smoking, and alcohol. Follow your doctor's orders for the next step of investigation, but it may have been a normal elevation.