Yes, sending credentials in plain-text is bad. I would be more worried about your password being stored in plain text. That data is just sitting there...waiting. defended by super 1337 TrendMicro security!
Since this password was sent in plain text at signup-time, there's a chance that it was still hashed/encrypted before being stored. Not a good chance, given the fact that they thought it was ok to send it in plain text at all, but still a chance.