You're overanalysing this single event. Unless you have access to the OFDM data you can never be 100% sure what exactly happened in what order. Take what you have picked up here and see what happens next time you find yourself in a similar situation.
As I pointed out before, rudestuff's explanation refers to the 757. The 737 is subtly different. For instance rudestuff wrote:
A /FL220B restriction will make no difference (because it was already going to do that) but an /FL190B will bend the elastic band down, forcing a steeper path ALPHA-BRAVO and a shallower path BRAVO-CHARL.
The 737 will do the same for the A-B path, but the B-C path will depend on the setting in the FMC I talked about before. If the FMC is set to geometric path on approach only it will calculate a level segment after B before intercepting an idle descent to C. If it is set to FULL geometric path descent it will behave as rudestuff describes. You really have to find out what your aircraft is set to before you delve too deep into these problems.