Travel Technology - Odd discovery-usb headseat as signal booster

^
By accident I left my USB headset plugged into my Dash.
Best reception I have ever had in my home-which gets very spotty coverage.

So is this unusual?

It is probably having some "undesired" (but really quite desired) RF interference that is turning your headphones into a large antenna.

Some Sony Ericsson phones' FM tuners use the headset adapter as the antenna. The downside is no FM radio over bluetooth headset.