"Is this concept of taking a certain melody and playing it over different chord progressions in different sections of the song "poor form" for any reason?"
I would urge you to reverse the thinking and realize that melodies don't get played over chords. Chords are supposed to support the melody. That being said it is quite common for soloists to structure their solos by following the "chord progression" but the fact is that the really great ones don't. They know how to create beautiful melodies that stand alone and the chords work under them.
Also, realize a few other things.
(1) That there are always more than one option for harmonizing a melody. Following the standard approach of multi voice harmony one has many possible options for building a support structure for the melody of a song and that many times the chords appearing in a chart don't match what the composer (in this case you) wrote.
(2) There is a connection between many chords within a key allowing for them to be used as substitutes for each other. The simplest example is the pair of enharmonic chords (Maj 6, relative min 7). For example in the key of C (C6, A-7) are the exact same chord just different inversions. There are other pairs. This allows you the composer to create much more interesting harmonies for the same melody (and this is a very common practice).
(3) Using chord substitutions, almost any progression can be converted in to a I-IV-V. Making that old cliche about Rock songs ubiquitous in all genres of Western music.
As one example I often rearrange classic standards so that the Real Book chords are all replaced with "unusual" subs. One example is All of me in C. I play the entire thing with chords from the relative minor A. I must stress that I do NOT transpose the song into an A minor tune. I play it in C as written but harmonize with a chord melody in Amin. It sounds great that way, real Latin feel but again the same old song.
As another example I would point out most anything written or arranged by Wes Montgomery. Though most players do the opposite of what you are suggesting, that is writing a simple chord progression over the melody then adding complexity to the solo section. West Coast Blues is a classic example for any guitarist. Standard 12 bar blues with some exotic subs and extensions but during the solo section he adds a half dozen new chords and a cascading stream of key changes. So in short the answer to your question is that it's NEVER in poor form to use multiple sets of changes for the same melody.