I'm not the author, who is in this thread elsewhere, but very curious what the bug is, if only to avoid it myself since I use micro constantly.
1. > tab
2. type some JS
3. > save
4. (prompted by Filename:) test4.js
5. File doesn't get saved
6. > save test4.js
7. File does get saved but syntax highlighting doesn't kick in.
Seems easy enough to avoid (after figuring out step #6) but little issues like these really throw me off.