How can you think that anyone can be upset for you replying late? We all have a life outside of Steemit, it is called real life and it's more important than this although this is becoming more and more important day by day 😀
Ok, jokes aside, don't worry about it, no one is expecting you to stay in front of the screen all day/night and write comments longer than some posts (mine for example).
Don't worry, just have fun! 😉