Thanks for those numbers.... when converted to US units you are at 637 pg/ml. This is above the 400 minimum, but not by much.
If you were taking any vitamins at all, and didn't stop them you could report with an artificial high.

Most of us here with PN keep our levels at 1000 or above, to ensure that the B12 is getting into the spinal cord and brain more easily.

You can also show normal levels of B12 if you are not converting it to methyl form. The old unconverted stays in the blood serum and will show up in the testing. Nonconverters, have a DNA mutation that messes up activation of B12 to its methyl active form. It is estimated that 10-30% have this variant either in heterzygous (both genes missing) or homozygous (one gene missing) form.

The posters here who have had this testing done have all shown some mutations.
Here is a link explaining in more detail:
http://doccarnahan.blogspot.com/2013...-big-deal.html

To check if your B12 is actually working, there is a test besides the DNA one, and it is called MMA. If the MMA test is low, that means that B12 is working in it right form to metabolize it away.
A high MMA result reflects B12 failure --hence no methylation going on.

This link explains the MTHFR mutation in detail.
http://mthfr.net/

This is becoming more commonly understood, as the information is only about 10 yrs old. But many doctors were not educated on this topic so remain confused or clueless about it.
Your folate levels were not in your post, but if they are elevated or if your MCV is almost out of range or high, they can be clues to the fact that B12 is not working for you.