Yes, Tim, you are completely right!
That was something that occured to me rather early Absolutely no symmetry whatsoever!
Thing is, I have never found a hires picture of Han's helmet to count the stripes. Until yesterday night, that is ...
After digging through everything I could lay my hands on, I found out, that on Han's helmet there are 11 Stripes on his right tube and thirteen on the left one.
Sorry to have hijacked this thread, back to Luke's helmet!