I have a strange resonance sound when the D or A string are allowed to ring out. Happens when plucked open and on the lower frets. Other strings seem fine, I did take it to a shop to get it setup and let them know about the problem and it has got better since the setup but definitely still there! Please see the video in the link below to see what I'm on about. Any ideas what it could be? It is a Chapman Guitar... ML1 i beleive. Has quite heavy gauge Ernie Ball strings which were fitted during the setup.

Would appreciate any advice, im a bit of a novice. Cheers