Hiya
Baby composting worms (Eisenia fetida) are most definetly pink, if you have small white worms they are probably pot worms which are nothing to worry about, they aid the composting process. Composting worms tend to swarm when there is low pressure weather systems about - it seems to make them wander prone!
Also Ive found that when your bin is almost full and the stuff is quite well worked over, you tend to get an explosion of worms and then they all disappear and you get woodlice in for a bit and then they all go and then your compost is finished and ready to use when there are hardly any beasties in it.
Hope that helps:-)