That address mined for about 2 months, not a week. See http://bitcoinrichlist.com/address/198aMn6ZYAczwrE5NvNTUMyJ5qkfy4g3Hi?charttype=balance It is possible that as he is trying to recall events from four years ago that he has simply forgotten how long he mined for and the exact number of coins. I think that's quite possible and so either this is him or perhaps he had something nearer 750 and not 7500 coins, and has misreported it, or of course he could just be a publicity seeker and the whole story is a hoax.

M