I'm back to 12 satoshis.  I've just realised that the reason I got more was that I triggered the reward points to double my base reward.  it had told me that it couldn't do it at the time as I had a reward going for lottery tickets but it obviously kicked in when that finished which just happened to co-incide with what I wrote on here.  Looks as though it will be a permanent thing for those not considered profitable.  I don't have another account or use a cheat so it can't be that.