I found this bizarre thing while doing some babel coding. I start by
putting this template together

#+name: leibniz_3
#+begin_src lisp :session :exports code :results silent

#+end_src

Then from this page
<ftp://ftp.cs.washington.edu/homes/tanimoto/ai/LEIBNIZ.CL> I copy this code
(some 40 lines down)

. . .
  (push (make-rule :goal (first r)
                   :pattern (second r)
                   :action (third r)
                   :name (fourth r))
        *rules*) )

into a C-c ' buffer. But when I return to my org buffer (with an additional
C-c '), it has done this:

#+name: leibtest
#+begin_src lisp :session :exports code :results silent
  (push (make-rule :goal (first r)
                   :pattern (second r)
                   :action (third r)
                   :name (fourth r))
        ,*rules*) )
#+end_src

Can you spot the difference? Subtle bug as it is, the code now has a comma
thrown in on the last line. At first I thought this was some copying crud
-- for example, if I simply highlight my code directly off this email (in
Chrome/gmail) and try to XWinows-paste (middle wheel mouse click) it in, it
throws in weird white-space crud -- but no, this comma add thing is only
from doing a C-c ' round trip! And no, it's not an issue of how I put in
the code: copy or type -- into the original org buffer or into the C-c '
buffer. Again, just a C-c ' round trip throws in this comma. Odd
coincidence, but this might have been legitimate CL code, except the list
needs a backquote too. This has been a hair-pulling, all-time-top-ten bug,
to be sure. And diff shows only this problem on the whole LEIBNIZ.CL file.
Any ideas what's causing this?

Lb