Olha só o que achei nas discussões no site da Apple:
"Is it safe to use alcohol swabs or Windex on an iPhone screen?
Page 51, User Guide: http://manuals.info.apple.com/en_US/iPhone_User_Guide.pdf
- Cleaning iPhone
Clean iPhone immediately if it comes in contact with any contaminants that may cause stains, such as ink, dyes, makeup, dirt, food, oils, or lotions. To clean iPhone, disconnect all cables and turn off iPhone (press and hold the On/Off Sleep/Wake button, then
slide the onscreen slider). Then use a soft, slightly damp, lint-free cloth. Avoid getting moisture in openings. Don’t use window cleaners, household cleaners, compressed air, aerosol sprays, solvents, alcohol, ammonia, or abrasives to clean iPhone. The front cover
of iPhone 3GS and the front and back covers of iPhone 4 are made of glass and have an oleophobic coating. To clean these surfaces, simply wipe with a soft, lint-free cloth. The ability of this coating to repel oil will diminish over time with normal usage, and
rubbing the screen with an abrasive material will further diminish its effect and may scratch the glass."
Eu acho que vou deixar ele sem a película mesmo, não deve ter danificado tanto a proteção oleofóbica.