Ionic required form controls not styled

Ionic Framework ionic-v3
1

I have a form in markup like this…

<ion-content padding>    
    <form [formGroup]="incidentForm">
        <ion-item>
            <ion-label color="dimmed">Survey Number</ion-label>
            <ion-input formControlName="surveyNumber"
                type="text"></ion-input>
        </ion-item>       
        <div padding>
            <button ion-button
                type="submit"
                [disabled]="!incidentForm.valid"
                color="primary">
                   Submit</button>
        </div>
    </form>
</ion-content>

I then code the formGroup like this.

this.incidentForm = this.formBuilder.group({
      surveyNumber: ['', Validators.required]
    });

My expectation is that the form input element would get a “red” bottom border. But that doesn’t happen until I input data, then remove it again.

Thanks
–tolga