Definitely could be bubs moving. I felt the first movements at 14 weeks exactly (and this is my first baby). I was so surprised I almost fell out of bed!

I think the fact that you're questioning it because it felt different to everything else means that it probably was your baby. Only time will tell. Don't be stressed if you don't feel anything for a few days, it takes a while for the movements (feeling them anyway) to become regular.