It's for my PC. It could affect resale in the future, but I have my doubts it will on the yellow label. I mean hell, Miller's auto is way harder to tell what it is than Stan's current Signature. Looking at what's sold on ebay, etc. the market is there whether it has the newer, non-pretty stan autos or the older ones. On a board like this, the older ones will fetch more buyers, but for the collectors a step below, I've yet to see any signs of it really affecting value.
That being said, it will be about 15 years or so before I sell this if all goes to plan for me retirement... so I'll worry about it then.
That being said, I've seen far worse stan autographs. But those will be the last ones I send. I got his sig on the books I wanted for my PC and I'm good.