Now I'm having doubts about it. I know for sure that with Transmission it worked that way, on second start all the torrents with missing files were paused. With qpittorrent, one hour ago, I was pretty sure I didn't need to unpause the torrents but now I'm affraid of missremembering something. As soon as I get home in a couple hours I'll test it to make sure.
Edit: confirmed, all torrents resume correctly without having to verify them.