Python CarTalks Puzzle

I just heard an old episode of "Car Talks" and they gave the following puzzle:
http://www.mscs.mu.edu/~paulb/Puzzle/palindromesolution.html

I wanted to see how quickly I could solve it in python without attempting to be efficient and ended up with this:

#puzzler #7 solver
#written by jim clampffer 4/29/13

#string -> bool
def ispalendrome(numberstring):
    return numberstring == numberstring[::-1]

for milenum in range(999999):
    mile = str(milenum).zfill(6)
    #check that last 4 digits but not last 5 digits are palendromic
    if not ispalendrome(mile[2:]) or ispalendrome(mile[1:]):
        continue
    #check that last 5 digits of mile + 1 are a palendrome
    mile = str(milenum+1).zfill(6)
    if not ispalendrome(mile[1:]):
        continue
    #check that middle 4 digits of mile + 2 are a palendrome
    mile = str(milenum+2).zfill(6)
    if not ispalendrome(mile[1:-1]):
        continue
    #check that all digits of mile + 3 are a palendrome
    mile = str(milenum+3).zfill(6)
    if not ispalendrome(mile):
        continue
    #got the answer
    print(milenum)

It worked. Cool.