Started exercising --> gained 8 pounds?!

Hi there!
I guess the title says it all. I started exercising for the first time in my life two weeks ago. I was at 137ish. As of this morning I'm 145ish. Now I know the scale can be evil but even my measurements are bigger.
I eat primal almost strictly. I do have cheese on a daily basis but no more than an ounce or two and its good organic cheese. Some of my fruits and veggies are local grown, some store bought and some organic. My meat is another thing. I try to get the good stuff but I have a husband who bitches at me til the cows come home (teehee.) Our seafood is almost always local. I have a weak spot for unrefined coconut oil, whey protein, unsweetened chocolate and olive oil. I don't eat many nuts. I do indulge in fruit. Sometimes 4 times a day.
So that's my food breakdown now for the exercise. I practice hot yoga at least three times per week because I'm shamelessly addicted. Since I started that I can't sit still. The exercise + primal eating woke up my toddler-on-speed genes. So I try to walk instead of drive places. Even when I have to drive somewhere I'll park up to a mile away from my destination. Sometimes my energy is still going so I take my children to the playground and chase them around. I'm worried about that because at a certain time of the night I'm just done. I'm so done I could pass out at 8pm. I don't mean to over exert myself, I'm genuinely having alot of fun.
I went from being sedentary to moving ALL OF THE TIME. Could it be the shock to my body? Is it confused and scared thus retaining a buttload of water? Any insight would help! (I don't want to buy new clothes in the sad direction)
A change in perspective is worth 80 IQ points - Alan Kay