When you see a favourite band has a new album out and think `cool, I'll check it out` and then discover you never actually heard their last album from like two years ago
Have just done this with No Age (didn't realise I never picked up Everything In Between). Also Marnie Stern, I've gone to listen to chronicles of Marnia and realised I never heard the previous self-titled one).
Obviously favourite is a relative term given the above, but does anyone else do this on occasion. Can't really figure out why I'm interested in a certain artist but didn't even notice I missed an entire album.