I lied to get a coffee break earlier

So I started this new job at the tech firm downtown last month. It’s been intense because there's so much to learn and everyone seems to know exactly what they're doing, while I feel like a total outsider. My manager is great, but also kind of scary, she’s always busy with meetings and deadlines, yet expects us junior staff to deliver quality work on time. The other day we were supposed to take our lunch break at 1 PM, but the project deadline was pressing and everyone decided to stay late instead to finish up. By 2:30 PM, I really needed a coffee break just to clear my head and get some energy back. So what did I do? I made an excuse that one of our team members asked me a question about something unrelated to the current project. I said it had to do with how we track inventory in our old system versus the new software, which is totally not true. It was just because my phone’s battery was dying and I really wanted a coffee. But I felt terrible lying to get this little break for myself. Is it really that bad to fib about needing 15 minutes to yourself? What if everyone else starts doing the same thing? How am I supposed to navigate all of this when even a tiny white lie feels like such a big deal?