Don't feel stupid! what you will learn if you read a little here is that everybody has a different "normal."
My O2 is usually 96-98, but my pulse is very high and would worry a lot of people. My friend's O2 is always below 95, but she feels no shortness of breath - it has always been like that. The same applies to body weight, blood sugars and other measurements. My blood sugar always registers "above normal range" but my A1C (the average over time) is always 5.3 or less which is excellent.
If the doctor is happy, and your husband is healthy you should relax. Unless he smokes or vapes - then there is cause for concern.
Sue