Light "Fluttering" or "Ticking" above 2-3k rpms?

Hello everyone, I am new to the forum and have been searching and reading through here for hours now about these cars. I recently bought a 2004 Passat (B5.5) and I really love how quite and smooth it is. I have one question for you guys that hopefully someone can answer: When accelerating, and only above 2-3k rpms, I hear a light fluttering or ticking from under the hood that sounds as if it's coming from the turbo. It's hard to say exactly where, and it's not too loud at all. I can't really hear anything with the windows up, but when I put the windows down (especially when driving next to a barrier or wall) I can hear this sound when the turbo spools up. I don't think it's valvetrain noise, because it doesn't happen all the time at low speeds and light acceleration. It only occurs under medium to hard acceleration when the turbo really spools. It sounds almost like someone sticking a piece of paper into a slow moving house fan. It's not a very fast moving sound, just a moderate "tap". I know some people have turbo issues that sound more like a dentist drill, and this is not like that at all. This is a light sounds that is not extremely fast. If this was valvetrain noise, wouldn't it make the sound at all rpms? :wrench:
Please shed some light on this if you can. I am probably going to take it to a VW dealership and have them look into it. I bought a warranty through a company called C.A.R.S protection plus (basic powertrain warranty). Has anyone had any dealings with this company?