I specify to my students what approaches I would like them to try, as mentioned, flapless are fine in most types. I call poor instructional technique if the instructor is laying into you. They should be happy that you got the aircraft back in one piece!
But really, they should make it clear what is expected. If they ask you to do normal T&G, and you go giving it all flapless and glides, then you deserve it. If he just told you to go and practice, that's exactly what you did.