supposedly freshly bottled wines with little sulphur can show some mousiness that will dissipate with a bit of age. i am not sure the exact reasoning behind it or how valid it is but i have heard it from quite a few natural wine makers. this is a flaw i especially dislike and tend to find it more often in reds and pet nats than whites. i think it is more common the higher the ph is. i never quite understood how certain wines become mousey after being open for too long but if you manage to drink quickly they are just fine. i actually had a magnum of ultime that after a few hours turned south. balagny’s wines tend to do the same. not even overnoy is immune especially in hot vintages. the irony is apparently there are some “non interventionist” producers using enzyme (lysozyme?) to clean things up.
I really like Dutraive and they age so well. I have never had a bad bottle of it unlike the poster above. Lucky me I guess.