well I tried with your string and it didn't happen for me, and when I checked with file it was ok... I would guess there is a problem with default encoding in text mate
$ file ~/Desktop/test1.txt
/Users/gplayer/Desktop/test1.txt: UTF-8 Unicode text, with no line terminators
$ file ~/Desktop/test1.txt
/Users/gplayer/Desktop/test1.txt: UTF-8 Unicode text