Just popped up out of exile and read this thread and felt I wanted to reply....my t has years of experience, and of course has a supervisor. I wouldn't work with her if she didn't and, in the UK, her registration wouldn't be valid. My t is also a supervisor, and her supervisor also will have a supervisor...like pyramid selling! My college tutor has been a supervisor and t, tutor and dr for years and has fortnightly supervision.
I guess I felt this was important to point out to balance other views on here. Also, anecdotal evidence that I, just personally, have been given suggests that it can be those T's who think they don't need supervision are often the most in need of checking/guidance.
So yeah, it might raise alarm bells for me. But, most important, is that your instinct is telling you something here, and you are the expert on what is right for you.