Ericka, thanks for your question. I am a father of four, with three boys: 7, 12, 15 years old. I definitely see this separation anxiety as a real problem. While "normal" can be hard to define, if my 7 year old did this to me, I would certainly want counsel myself.
What kind of relationship does he have with his Dad? Was there recently a traumatic event that may've lead to these separation anxiety/tantrums?
Maybe you can encourage Dad to plan some time in advance with his son, then let his son antcipate the next time together. It could be that he feels insecure because of something that happened recently or even a nightmare or dream about Dad. Providing more "normal" time together will heal this in time.
Hope that helps!