So I brewed a Belgian quad last year and bottled in both corked belgian 750s and 12 oz crown-capped bottles and carbed to approximately 3.5 vols. and within 8 months the corked bottles were almost flat but the capped bottles pour a nice, dense, rocky head. I didn't use any kind of foil, shrink-wrap, or wax seal. The bottles were stored upright and undisturbed in the coolest room in my basement (55f winter- 70f summer). My corker inserts the corks with about 3/4" protruding and they are not dried out. Has anyone else experienced this? Should I seal with the bottles with something? I'd like to use these type bottles in the future but not if my time/effort/patience results in flat beer! What did I screw up?