Air in fuel filter

[Okiedokie]

I have an Airtex electric fuel pump mounted on the frame rail just in front of the gas tank on my 46 coupe. Yestereday I encountered a long slowdown on the highway due to an accident after driving 1 hour or so at 70 mph. After creeping along for about three miles, as I accelerated back up to highway speed, the car began to stumble and hesitate. No doubt in my mind it was fuel related and it eventually began to clear up. It was time for a  break anyway so I pulled off at the next exit. I opened the hood to look things over and noticed air bubbles seeping into the clear fuel filter. I am assuming that is what caused the stumbling. Any ideas as to what might cause that? Thanks, Joe

[Harry]

Heat?
Vapor lock?