PIL image size after rotate

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Listers,

I have a very simple script that rotates images using PIL.  After 
running, the output images are about 1/3 the file size of the input 
image.  The file attributes indicate they have increased in resolution 
from 72 to 96 ppi but have the same radiometric depth. Does the PIL 
rotate method apply a hidden resampling? Why are the output images so 
much smaller?

from PIL import Image
import glob, os

indir = r'C:\Users\Me\Pictures\export'
for infile in glob.glob(indir + '\\' + "*.jpg"):
     print infile
     file, ext = os.path.splitext(infile)
     im = Image.open(infile)
     im2 = im.rotate(270)
     im2.save(file +"_rotate.jpg", "JPEG")
    #  os.remove(infile)

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