This is a weird one, but sometimes PL on my Nexus One will not play parts of the audio. The background track for the area is always there, but sometimes the weapon firing sounds and/or the emote sounds (but not necessarily both) don't play. Logging out and back in doesn't help, but doing a “force stop” and restarting PL always seems to bring it back.

BTW, PL on a Galaxy Tab is SWEET!