this is a quick one. after realizing that my ino files did not have proper syntax in vim, i did some googling and found this.
but it needed a little more to make it work with my setup.
so i added:
autocmd BufNewFile,BufReadPost *.ino,*.pde set filetype=arduino
~/.vim/ftdetect/arduino.vim — this vim file is not the syntax file but an empty file under ftdetect.