Hi
I'm a hospital Doctor in the UK. Immunoglobulins are part of your immune system and whenever people have blood tests done there's always a small chance that you can get an abnormal result through sampling error even if there is nothing wrong with you. The question is are you well or do you have recurring infections?
I'm sure that if you have this checked again in the near future it will be within the normal range. Have a chat with your GP if you still have any concerns and get it checked again. Hope that helps.