Monokote holds up a lot better too, at least in my experience. Every Ultracote plane I've done has had lifting seams after only a few flights, and I'm pretty conscientious to clean and seal them down. Monokote has stayed on a lot better for me.

To fix your seams, if you used a sandable primer you could do a few layers of building up and sanding down. Switching to the same brand's high build primer will make the job go quicker.