Is this the bag?
The classic styles do have the creed stamped on the inside (not sewn on a patch), plus I think some of the older serial numbers (REALLY old) have 3 digits and then 4 digits... but some of the other factors you are describing seem suspicious. Does the dust cover look like the fake ones shown on this page?
Spot a Fake Coach Bag | Designer Bag & Purse Blog
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Edit:
Ah! Finally found a pic of that style's creed:
http://i3.ebayimg.com/03/i/07/f4/03/c1_1_sbl.JPG