Hello~It is probably not serious, but given your symptoms and the threat of Covid-19, I would try to get in to see your physician, it is always better to be safe than sorry.
Hello and welcome to the forum. Thanks for the question. You are monitoring your O2 level at home? Do you have asthma or any underlying condition? Have you been sick at all lately? Do you have a cough or fever? Those are the hallmark signs of covid-19. Your blood oxygenation level is still adequate even though it is lower than where it typically is for you. Between 75 to 100 is often considered normal with most being between 95 and 100. When it dips below 90, it is considered to be low and warranting a call to your doctor. Under 60 is when it gets dangerous. If you dip below 90, I would call your doctor.
Here's an article. https://www.healthline.com/health/normal-blood-oxygen-level#symptoms
So, again, if your level drops below 90 or you have any symptoms of confusion, shortness of breath or chest pain, please seek immediate care from your doctor. They also are much more open to discussing these matters on the phone to prevent people from making trips into the office or hospital. Let us know how you are doing.