Weight gain from strength training

Hi everyone :)

I just weighed myself after 3 weeks of FB Strong, and found I have gained 4lb/2kg. I haven't seen a change in how I look, so I'm hoping this is muscle gain... I was not overweight when I started (was 130lb before, height 168cm)

My question to you guys is, how much weight have you gained from strength training? Did it feel weird? I am having a mental battle with seeing weight gain as a good thing!