Focalink ocarina question

[dspmusik]

I have 2 Focalink ocarinas (Soprano G and Alto C), and they are my favorite that I own. Excellent pure tone and play very in tune with themselves.
However, played with regular/light breath pressure (not super light or under blowing) it plays almost perfectly a 1/2 step flat. Both of them. To get it in tune, you have to really blast it, especially the lower notes.
Has anyone else experienced this? My Hinds and Mountain ocs are not like that, but they are inline, these are sweet potato.