No, it’s not normal. Your pressure release valve might have not been set to sealing or might have only been halfway kind of there – maybe it moved a bit (or a lot) from where it should be. This would cause extra steam to be released while it was coming to pressure. This loss of water has happened to me while I was cooking potatoes. The Instant Pot will still eventually come to pressure it just loses too much water along the way if it's not completely sealed.