Interesting - I tried creating a file by that name in OS 10.5, but when reading out the resulting name, the last two combining characters (U+0304 and U+05ae, corresponding to cc 84 and d6 ae respectively) had been transposed, presumably for reasons of canonical order. I had no problems removing it afterwards.
This would explain why you had trouble removing the file but now how it came to be created in the first place. I have heard claims that the normalisation algorithm in OS X has changed between versions; perhaps you upgraded your system between the creation and removal of the file? It could also just be a plain bug, of course, or a RAM single-bit error, etc. If you can reproduce it, I'm sure Apple would like to know about the bug.