I wouldn't trust him either, he's looking out for himself to "steal" it from you.
Like I said, if it's a forgery, it's a darn good one. The style of the numbers look correct, and they all line up and look like they're the same depth.
If someone hand stamped those numbers, you should be able to see some inconsistencies, if even a slight bit.
well the z is alittle out of line just by a very little, but other stampings i have seen(not dz) the last letter is off alittle also. so im just alittle.... yeah..