Yes, the tree is grafted somewhere around an 5-8cm below the first branch where you see the texture of the bark changes.
White pine would develop rough bark eventually, but the process is much longer than black pine. Since your pine is actually growing on white pine roots, it should be more vigorous and stronger. Many folks in this area have difficulty with white pine. It is probably a good idea to keep the pot itself shielded from excessive heat. I have recently found this year that those trees that have just a bit of protection from summer sun show better needle color.
Hopefully your tree wasn't bareroot at import? This can be especially tough on pines. When imported to the US from Japan, they must be barerooted, consequently we don't really do anything for about 18 months to be sure the tree has stabilized and is growing well.
I, too, in 5 years time hope to be a little embarassed by the photos I am uploading today
Regards,
Matt