A scenario like this is likely not to make it into the refurb pool. Except for one instance I never seen anyone mention getting a refrub from Canon that was less than "new" cosmetically. The one instance I'm referring to was an individual that supposedly got a refurb with like 20000 clicks and some very obvious cosmetic shortcomings. That just didn't add up for a Canon or Adorama refurb.
Personally I would forgo any extended warranty. Canon gives you a 90-day warranty. If the camera is well exercised duing that interval any latent defects will show up.