Never mind I found the answer. If anyone in the future comes looking for the answer to this:
If light goes from a ---> b with n(a) > n(b), the reflected wave has no phase shift
If light goes from a ---> b with n(b) > n(a), the reflected wave has half cycle (180 deg) phase shift
n above is...
For instance, I know if a light wave traveling air (n = 1) enters a thin film of water (n = 1.33), there will be a phase difference.
My textbook sol'n manual states that there will be a 180 degree phase difference for a wave of light that reflects of the top of the air-water boundary, but NO...