hmmmm.... I ran a test (without the change above); and its saving the zipcode properly:
zipcode
06076 www.viperalley.com/classifieds/
1536
2508244224
29693256
4139935584
29687221
Why do you think its not finding the zip code or removing the leading zero?
I made a slight change to the line above, different line number; although it will have no effect, but should be done anyways.