Well, depends on how friendly your fc mates and how close you are to them (and vice versa), it could be some kind of joke
you know... joke like...
you talk bad to about your best friend directly in front of him/her (especially if he/she ask about him/herself to you),
but praise your best friend to the sky if asked by stranger...
call me naive, but usually if friends said something bad about you directly to you, they have good intentions (which is to motivate you to be better at things)..
but if you still feel uneasy about it, you should ask about it to said persons, to relieve your stress...
by asking directly, you should be able to pass judgement whether you better stay or need to find another circle...