Not so much as fooling yourself, but I agree with the OP your method isnt really 'original' in the sense that it's indeed exactly the same as the 'standard' one, just a tad different in how you explain the math. E.g. 'if not ending in 00 throw away...' is really just the same thing as 'except when divisable by 100'.

To add to your comment, being divisable by 400 is also the same thing as throwing away the 00 and checking the remaining is divisable by 4. One explanation is just a rephrasing of the other for the exact same method.