I think it's normal and not incorrect. Deaf or not, we sometimes want to be alone. Maybe we are tired, or just want to be on our own thinking.
Sometime, it's difficult to tell someone "I don't want to speak with you right now". So ignoring them might be a kind way of saying "not now". People usually get the message, they may not like it, but the message is received.
Although, in occasions, you may not want to speak with someone, period! Let's say a drunk person or someone making an unwanted advance on you. Ignoring them might not work so a direct approach may be required.
Whatever the situation, deaf or not, think about how you would feel if you were the other person in a given instance. This usually tells you what to do.