[Pharo-project] Invalid utf8 input detected: now what?

Hello all, I got an error (on Ubuntu 9.10) trying open an old text file that I created on Windows some time ago. The encoding (if gedit's save-as dialog can be trusted??) is Western ISO-8859-15; resaving as utf8 lets me read it. So, is Pharo working by design? Did I do the correct/only thing needed to read the file? What should I be asking? Is there anything I can do to turn this into a useful test/debugging example? Bill