Is it normal for babies weight gain to slow down and what should I expect?

My baby is just 3 days away from 3 months, and I have takin him once every two weeks to get weighed (for my own peace of mind) he always gains right at a pound every 2 weeks. Yesterday when I took him to get weighed, he had only gained 10 ounces in 2 weeks. He started out so small at only 5 pounds, so he's still not up to "average" for his age. I know he has a growth spurt coming up soon, but is it normal for weight gain to slow around this age? What should I expect as far as weight gain for the next several months?