1.9 dci air in fuel pipe

[iash101]

Hi guys!!
I cleaned the egr valve on my 1.9 dci as it turns out it was pretty clean,however i noticed quite a large air buble in the fuel line,its in the thicker line i think its the one that comes from the tank (its not the corrigated one that goes to the pump) I serviced the car a few weeks ago including the fuel filter.can anyone tell me if these bubles are normal ?? if not any any sugestions on how to get rid of them
cheers iash101