I agree with my friend, Stevepetergal, that the only "opening up" a uke does is when it cracks from low humidity.
I own a solid Mahogany Silver Creek (on musician's friends) that is such a hunk of crap that it could only seriously function as a doorstop. I didn't love it when I bought it, but thought some Aquilas would help--which they did. So, I kept it. Now, a year later, the fifth fret is buzzing, and I drilled in a Shadow pickup and, even electrified, I like it nada. Every time I even look at it, it makes me ill. I keep it in the back of my pickup truck., and the irony is that, when I'm on the go or someone wants an impromptu song, that's the one I now have most handy. Ugh! Moreso than even my buzzy crapola Cordoba CK25, which is a real hunk of doo-doo itself. I told my wife that, when I die, she can cremate me with my Koaloha or Donaldson (I know, I know..but I want to play them in Hell, okay!?)--just my poop luck, my non-uking wife will likely think the Silver Creek is the one I want to be burned with since it's in the back of my truck, and that'll go into eternity with me!
I swear, if that Silver Creek (or the Cordoba, for that matter) sits with my ashes in a clear jar (so I can see out) atop my fireplace mantle for eternity, I'll come back and haunt those luthiers, if that's what they're called, at Silver Creek until my buns are blue.
So, yeah, original poster, I have the same experience.