You can let your batch 'overbrew' up to a week longer to get a really nice thick one started, then cut back to the brew time that gives you the best flavor/sweetness.
Other than that, there have been 'warnings' not to use organic tea, but it doesn't sound like a mold issue.
I'd be more suspect of all that fizzyness just making little air pockets and if it's still a thin SCOBY, it hasn't filled in by the time you are brewing it up, ergo, it's a 'cosmetic' issue only.
If the kombucha tastes good to you, no worries!
Do you boil your water for 5 minutes with the sugar, then steep the tea bags in the freshly boiled water for 10 mintues? That could also affect it, but not too much. It just helps kill off anything you DON'T want, and allow your new batch to get off to a good start.
Also, are you adding in a full cup or two of the previous kombucha tea, to get the acidity adjusted right from the start? That helps the new SCOBY grow a bit faster/thicker also, without having to go extra time.
I just took mine out at day 6, and the new SCOBY was thin, with a few holes...but the kombucha tasted awesome to me! I drank a full 12 ounce glass of it, usually I only drink a few ounces on 'brew day'....
I'd not worry, unless you are shipping them and want them 'pretty'.
