In my experiences, Hefe's are best brewed at lower temps ie. <65*F. It seems to help keep the esters in line. I also find that a nice, healthy 2L starter helps too. Although it doesn't sound like you're having an ester problem.
I'm not exactly sure what the sourness is you're experiencing but, depending on the cause, it might not condition out.
Hefe's can definitely be tricky at times. It's a simple brew, but relies so heavily on yeast character you don't have much wiggle room concerning fermentation temps.
A word about drinking hefe's "young..."
I find a lot of people say they're best young, but in my experience sometimes a little age helps them condition rather nicely. After a few weeks in the bottle (and a couple weeks from pitch before that) I think they're quite enjoyable. While still drinking them considerably "younger" than other beers, it's certainly not the 2 weeks I sometimes hear. The 2 weeks applies to kegging, not bottle conditioning.
Again, IMO 9 days is a little early for worrying. I'd let it sit a little longer to see if it clears up.
Would you say the flavor you're experiencing is getting worse?