Reminds me of the story about the double bassist who shows up late for a rehearsal and is obviously out of tune. The conductor asks him pointedly and sarcastically if he'd like a few minutes to tune and he replies, "why, aren't we doing it in the same key as last year?"
Seriously, though, I can see where if one hasn't yet developed a very good pitch sense one could go for a few weeks thinking one was in tune (after the strings had settled) because some string sets stretch pretty evenly and the uke may not go badly out of tune with itself for a couple of weeks, at least. Of course, as soon as one plays with others they are going to discover that they are A) out of tune with the other instruments that have been recently tuned to concert pitch and B) others may have a better ear for pitch and hear how even how ones uke has gone out of pitch with itself.
And then...I think we've all seen youtube videos that make us cringe and quickly hit the link for some other video because the tuning is so awful. I've seen some instruments (not just ukes) that were so far out of tune with themselves that you wonder why the person has any interest in playing music if their ear for pitch is so poor that they can play an entire song on an instrument that is not even close to being in tune with itself.
About a year ago we had a young lady singing and playing electric guitar in our band. She was borrowing one of my amps and about a half hour into rehearsal one day she says, "I can't make this amp sound good." I was on the other side of the stage with the drums and another electric guitar between us so I couldn't really hear her but I went over to see why she couldn't make the amp sound good (it was a pretty decent modeling amp). I'm tweaking knobs and I tell her to strum the guitar. She does. I say, "no, I mean strum a chord, G or something." She says I am. Whereupon I took the guitar and proceeded to tune the A string back to A from A sharp... LOL
John
John