Why can I see air in the fuel filter when idleing?

I was noticing yesterday that sometimes when my car is idleing I can see air apparently coming through the fuel line into the filter (I have a clear fuel filter, obviously). The air then gets sucked through the screen and carried to the carb. Is this normal? Could it account for some of my less-than-perfect idle? If it is sucking air at idle, what does this mean is going on at higher RPM? Do I probably have a leak in the line somewhere (the rubber hose between the fenderwell and pump and the short piece between the metal tube from the pump to the filter + carb is all new), or is could something be wrong with the pump? Sorry for all the questions, and thanks for the help!

'65 289 4V Edelbrock 1405 600CFM C-4 yada yada yada