It took me a while to realize that gmaxwell was talking about secretly recording the audio interference from a nearby compromized computer which would then be retrieved and decoded by the attacker at a later time.
Actually, from the computer the Trezor is connected to itself (after all, the point of the Tezor is the assumption the host computer is compromised); nearby would be an even more impressive stunt-- in terms of nearby but not connected; that would better be done with a software defined radio receiver (e.g. not merely a remote compromise).
All of that is a long shot, but thats the annoyance about defense; you have to defend against all attackers, and an attacker may spend a lot of time and resources on a single valuable target. It's quite hard to be confident that you do not have an exploitable weakness. If you're sure you're secure you're probably not being creative enough.