The only reason I use BitTorrent is to download Linux distros, Open source apps and large documentation files. My ISP contacted me once and warned me:
Ok, you aren't downloading anything illegal or pirated, but our network traffic doesn't allow p2p in general (implying that I should stop).
So, I chose a VPN and tunneled p2p client through it and soon committed a mistake of not deleting my default gateway from the routing table. When the ISP connection dropped, and reconnected later, VPN was still attempting a reconnection. Meanwhile the torrent client might've switched to the default gateway and resumed downloading (for half an hour) exposing my IP to the tracker pool.
My doubt is, would the above-mentioned scenario expose my torrent-IP permanently to the ISP? Are the peer-IP's kept forever in the tracker's list? How long does it take for an agency (like the ISP) to gather such data.