It is entirely possible that it was a drive-by that had several thousand songs in his/her shared folder. You don't have to actually download them at the time, you just have to have them available for download. If someone popped on tour network with 150,000 songs shared and the RIAA happened to scan your ip at the time, you appear to be sharing 150,000 songs. Yeowch.... Sooooo glad I am running completely wired connections.