Thank you very much for your answer! Yes you are right, I have had the same problem with my Felicie, which I have sold because of the curly edges.Unfortunately, i feel like it's bound to happen with canvas flaps similar to the felicie... It's probably due to the heat causing the plastic (the coating on the canvas is technically plastic) the curl up... The good news is a leather spa might be able to fix the issue for you (you can also try heating it a bit with a hairdryer and sandwiching the flap in the book to straighten but only it you're ank comfortable)
For the future I don‘t buy no more bags with flaps. The Mini Dauphine will be the last one, and I will let her go now .