I would keep your eye on it. I had a rasbora recently who was doing that. Was hanging out at the bottom part of the time, then shoaling with the others part of the time. I found him dead stuck to the filter about a week later. I think it was being bullied a bit by my lone zebra danio. (I am still looking to rehome it.)
"Emo" tetra!
I fed them this morning and he didnt eat. The others don't seem to be bullying him, infact they seem to go up to him, wait in front of him, swim off a little, and go back when he doesn't follow