Would you be annoyed being left on read?

If you were just in a relationship for a few months, and the person you were with doesn’t text you back but leaves you on read for several hours (they tell you the reason is because they fell back asleep after reading your text- yet messaged you back as soon as you asked if they were ok.) Say it’s happened several times with in a week. Would you be annoyed, or would you be understanding?

I asked a friend and they said that seems odd and they’d be annoyed about it. Just curious what you all think?