grammaticality - Correctness of omitting a definite article or a preposition

I am writing an essay about my university experiences and a suggested correction from an English Ph.D. sounds wrong to me.

The suggestion is

In our meeting to discuss the spring semester of my junior year, my adviser set forth a challenge.

She made a similar correction later,

One graduate course had been sufficient to consume my time in the fall semester.

As a native English speaker, both of these corrections sound like grammatical errors to me, but I do not have the linguistic knowledge to articulate exactly what, if anything, makes them incorrect. (I spend much more time on math.se than english.se!)

Are her suggestions correct?

Answer

Time periods can be used without articles. A different example:

One graduate course had been sufficient to consume my time last semester.

I personally find it awkward to use "fall semester" instead of "last semester" but it's the same basic idea.