It is common to have really vivid dreams during pregnancy! It's a combination if everything from what I've read/heard. Hormones, stress, happiness, excitement, unanswered questions, things you have forgotten.... You name it and it will add into the why of getting these dreams!!
Only problem is some of the dreams can seem too real. :(
I woke this am after some strange dreams. This is my third pregnancy and because my youngest is 14, I don't remember if the other two were similar. Hubby and I are both thrilled about the pregnancy and everything was planned, so I don't feel stressed about the pregnancy, but I woke up thinking that I haven't felt the baby kick in a while and it worried me. So first thing before getting out of bed, I got out the Angel Sounds dopplar and checked for the heartbeat. What a wonderful sound.
I guess it could be stress or something you ate last night, or just hormones. Who knows. ;-)