408 fix recheck

[TysonMN]

Fixes #408

[dharmaturtle]

Passes in my use case as well. A few very minor suggestions, but otherwise LGTM!

As side commentary, I'm not fond of making the test dependent on the shrinking behavior, but I don't feel strongly about it. One possible solution is to steal from my example in #408:

        let mutable target = false
        property {
            let! _ = // some random unused gen
            Expect.isTrue target
        }

But again, I don't feel strongly about this.