Lenovo x220 + Chrome + iPhone = Just... Plain... Weird behavior

Here's the set-up:

Lenovo x220 running 64bit #!
Google Chrome running as web browser
Laptop and iPhone charging on the same Lenovo 90w adapter (e.g., the iPhone is *not* directly connected to the computer via USB)

What's weird is that *every single time* I open a new URL in chrome (or refresh the current URL), the iPhone chirps as if I just re-plugged USB power. I am simply baffled by this behavior.