Perhaps it needs watering, Mightymo. we've had a really dry spell ---before all the rain, so it may have been suffering, especially if it's in a pot. Try looking it up on the net, to see if there are any diseases that affect bay trees. I don't know of any, sorry. Good luck with your tree. Annie

No personal experience, but don't bay leaf suckers do this, too?

Yes, they do Tug, although more usually its only one edge, and it looks thickened and yellowish, and if you pull it open, there's often webbing inside - leaves at shoot tips are usually most affected, though if you didn't notice when it first started, more leaves may have grown by now. Check for Bay Sucker, mightymo - if its bad it needs treating with a spray, although I don't know what now because malathion's been withdrawn. Provado may make something for this pest. Otherwise, water well.