As everyone else has said, totally normal.

To answer the question about pulling boys...
I separate out my males, and give my nursing girls their own tub. I give the boys 1-2 weeks to get the job done, then send them on their way to the next set of females. Works best for me so I can better predict the due dates, and so I can keep track of which litters belong to who. This also gives the girls some breaks between litters.