I was selfish and it makes me sneaky

I left the office at 9 and didn't say goodnight to anyone because they were going to work till midnight ( salary) I'm hourly, but I was done for the day. I worked from 8am to 9 pm. There may be bonus for those who work till midnight tonight --- it's an IRS business tax deadline at midnight. Anyhow, it was a little sneaky of me to avoid saying good night to my co workers. I did sign off to the boss. I guess I didn't want to affect their energy in case they were staying till midnight.