Curious, does your husband do the root beer the REAL old fashioned way (using actual sassafras bark and wintergreen leaves) or modern oils (nothing wrong with using those, I've had great root beers made that way. And are you getting the carbonation from CO2 cartridge/ carbonated water or adding yeast and letting fermentation do it (making a root beer that is mildly alcoholic)
That reminds me of a funny story. We made rootbeer once at camp, with oils (as the nature section the ORIGINAL plan was to do it the old fashioned way, but it turned out that ten or so ten year old kids do not have the strength to dig down to the roots of sassafras trees and hack the bark off. And it was a bad year for wintergreen there) to out surprise, we did do it with yeast (I actually asked the councilor, and he actually said "oh no, yeast doesn't make alcohol)
We got to taste the results about two weeks later. Like some people I pooled so as to have some spare bottles to take home with us. I found it probably some of the best rootbeer I had ever had. Only stinger was that at session end I went to get my bottle only to be informed that they had all exploded (since the teacher didn't know that yeast made alcohol, I imagine he also hadn't realized that he needed to heat the bottles when the root beer was done to kill the yeast off and stop fermentation)
Oh, and if you hubby ever decides to diversify a bit and do SPRUCE beer, let me know. I LOVE a good spruce beer (hopefully if he ever does, by the time it is ready, my weight will have dropped to the point where my blood sugar is steady enough to drink a spruce beer without worrying what it will do to me.)