Beautiful sails, Jd,, that can really be flattened to "climb the wind"!Car father forward?
But the probable cause is that the jib's luff does not have enough hollow.
Headsails are cut with negative roach (hollow) so the leach does not flutter. Jibs are allowed to have less, and often the sailmaker cuts it too flat and flutter occurs. I would ask your sailmaker to recut the leach, or add vertical battens. He knows bettter. This is a common problem.
This jib would flutter with this much roach without battens.
When we took off cruising on our '93 F-P Antigua 37 cat 20 years ago we had UK build a fully battened furling jib with a nice roach to replace the small, scooped-leach Solent jib. Two full length vertical battens and two partials gave us about 25% more area with same overlap, and a very nice set when reefed to either of the full battens. Over 20,000 nm's on it and no flutter with mod. L-L tension when we sold her in '01.
Pete