Yes, must be the pan. It's not teflon coated and I didn't use any treatment on pan or parchment.
Cake was cooked. When it started to fall out I turned it over and it sank a bit, but it's edible.
Thanks for your response.
Twice now when I have taken Chiffon and Angel Food cake out of the oven and inverted the pan as instructed the cake has fallen out of the pan. The cakes have been done I think, firm to touch and I have not...