Cake disaster

It's not the end of the world, but, for the second time ever, the fabulous Breton chocolate pound cake exited from the tube pan in two pieces. With one piece stacked atop the other, the cake doesn't obviously appear to be damaged. Was it not left long enough to cool and shrink away from the sides of the pan? Should it have been loosened with a knife? Not enough butter and cocoa coating the pan? The pan's become misshapen and beaten up over the years. Does that have something to do with the exit difficulties? This pan was acquired long ago at the Thrifty Drug in Gallup, New Mexico.