Gaining weight too fast?

jadebuilding

Hi, I'm a fairly new weight gainer with a quick question - when I signed up 3 weeks ago, I set all my info to the correct settings (put my activity to sedentary & added in exercise manually for greater accuracy), & put my goal to 1/2 lbs gained per week.

The problem is, I've gained 3 lbs in 3 weeks, when I should've gained 1 1/2. I've been eating the right amount, no cheat days - what gives? If anything, I've done more exercise than I've logged, so it's not that, either. Could it be muscle?