Jules - unless you were lurking here you may not know this but I fired my OB at 21 weeks. There were several reasons why, but the primary thorn in our side was the whole P4 issue. From very early on he disagreed with me being on it. And the conflict just grew worse over time.
Not wanting to put unnecessary thoughts of concern in your head - but please do know that if at ANY point in your PG you're not happy with the care or treatment you are receving - DO NOT feel bad or scared to change OBs. I came to find out it happens ALL THE TIME.