I'm not an expert on the arcana of Perl variable scoping, but from a purely logicial point of view, I would say since you declared $zip in the loop with a my, it is creating a new $zip on every itereation. Therefore, you may want to either undef $zip, or move the my $zip outside the loop and then just do the $zip = new ... (without the my) inside the loop.

Either way, it may be a good idea to undef $zip or even call the DESTROY method explicitly to insure it has been discarded...

P.S. You should do the same thing with all the other values you declared in side the loop...

P.P.S. Thinking about it, I would move all the my's outside the loop. Seems like wasted time to redeclare them on every loop. Might slow down the processing if you are going through enough files.