Ionic 2 RegEX validation not working

I am trying to validate an input field that should allow only positive numbers greater than zero, and for this I'm using Validators.compose() with some rules. The problem is that I can't validate this field, somehow it isn't working as expected. Am I doing something wrong? How could I fix it? Thanks

TypeScript code:

export class SignupPage {
    public signup: FormGroup;

    constructor(public navCtrl: NavController, public navParams: NavParams, public formBuilder: FormBuilder) {
        // setting up sign up form
        this.signup = formBuilder.group({
            "name": ["", Validators.required],
            "age": ["", Validators.compose([Validators.required, Validators.pattern('^[1-9]\d*$')])],
            "city": ["", Validators.required]
        })
    }

    onSubnmit(form) {
        console.log(form);

        let user = {
            'name': form.name,
            'age': form.age,
            'city': form.city
        }
    }

HTML Code:

<form [formGroup]="signup" (ngSubmit)="onSubmit(this.signup.value)">
    <ion-list class="signup-input">
        <ion-item>
            <ion-label floating>What is your name?</ion-label>
            <ion-input type="text" formControlName="name" [class.invalid]="!signup.valid && (signup.controls.name.dirty || submitAttempt)"></ion-input>
        </ion-item>
        <ion-item *ngIf="!signup.controls.name.valid && (signup.controls.name.dirty || submitAttempt)" >
            <small>Please fill out this field.</small>
        </ion-item>

        <ion-item>
            <ion-label floating>How old are you?</ion-label>
            <ion-input type="text" formControlNale="age" [class.invalid]="!signup.controls.age.valid && (signup.controls.age.dirty || submitAttempt)"></ion-input>
        </ion-item>
        <ion-item *ngIf="!signup.controls.age.valid && (signup.controls.age.dirty || submitAttempt)" >
            <small>Please enter a valid age.</small>
        </ion-item>

        <ion-item>
            <ion-label floating>What is your city?</ion-label>
            <ion-input type="text" formControlName="city" [class.invalid]="!signup.controls.city.valid && (signup.controls.city.dirty || submitAttempt)"></ion-input>
        </ion-item>
        <ion-item *ngIf="!signup.controls.city.valid && (signup.controls.city.dirty || submitAttempt)" >
            <small>Please fill out this field.</small>
        </ion-item>

    </ion-list>
    <ion-grid>
        <ion-row>
            <div class="signup-btn">
                <button ion-button block width-90 type="submit" [disabled]="!this.signup.valid">Get in</button>
            </div>
        </ion-row>
    </ion-grid>
</form>

And this is how it looks like: