Put it this way if her dog took offence to your dogs sniffing around and went for them and yours retaliated and hers got injured, you would be hel responsible as your dogs weren't on a lead.
Sorry if it seems i'm taking the moral high ground i'm not, i'm just trying to make you aware of the law.I never walk my dogs on a lead except if i'm near a busy road, i do however call my dogs to heel as soon as i seen anyone with dogs coming towards me