No, it isn't. The rest of your post makes a good point, however. How big is this Corn and what are his temps? We're just coming out of winter, he could just have decided to go off feed for the jiggy season - especially if temps are a little on the low side. Are mice big enough for him now? Tried medium rats? Is he coming into ecdysis (shedding)? A good feeding Corn will usually continue to be just that, unless there's a good reason. Stay away from the wild rodents, they'll give it all sorts of nasties
If it doesn't eat offering #1, wait a week and try again. Don't handle it until