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The following statement is often made concerning reflection on glass:

"When light is normally incident on a glass surface, about 4% gets reflected and the rest is transmitted. The reflected wave is 180° out of phase with the incident wave."

In my opinion, this statement is only true if the slab is finite, since then another reflected wave (this one in phase with the incident wave) from the other surface of the slab interferes and explains why the intensity of the measured reflected light is between 0% and 16%, depending on the thickness. (There is also the fact that the measured reflected wave is generally not 180° out of phase. It is 180° for maximum reflection only.)

Thus, if the statement is made with reference to semi-infinite glass (which has only one surface), which is often the case, it must be wrong.

Am I right?

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"When light is normally incident on a glass surface, about 4% gets reflected and the rest is transmitted. The reflected wave is 180° out of phase with the incident wave." In my opinion, this statement is only true if the slab is finite,

That statement comes from Fresnel equations, which say that when a wave pass from $n_1=1$ to $n_2=1.5$, the reflectivity is $R=(\frac{n_1-n_2}{n_1+n_2})^2=0.04$, without considering a second surface. You can surely take the second reflection in consideration and use interference, but the 4% from Fresnel is about a single surface (to eliminate the second one, often you find it diffusive, or wedged, or absorbent etc.). See also this question.

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