Jacob, Jacob and Sons

A question came up in Torah study this week as to whether the order of Jacob's sons in Exodus 1:1-4 was significant. It took me a couple minutes to refer back to Genesis to confirm what I was thinking, by which point the discussion was three or four topics beyond that question, and I didn't feel like trying to take us back, but:

1:1] These are the names of the sons of Israel who came to Egypt with Jacob, each coming with his household: 2] Reuben, Simeon, Levi, and Judah; 3] Issachar, Zebulun, and Benjamin; 4] Dan and Naphtali, Gad and Asher. 5] The total number of persons that were of Jacob's issue came to seventy, Joseph already being in Egypt.

Reuben, Simeon, Levi, Judah, Issachar and Zebulun are Leah's sons, born in that order. Benjamin, tacked onto the end of those six brothers, is Rachel's younger son, Joseph (already in Egypt) being the elder. The break after Judah may refer to Leah's having had the first four before any other wife or concubine had a child.

Dan and Naphtali are the sons of Bilhah, Rachel's maid, who were born before Gad and Asher, the sons of Zilpah, Leah's maid.

So the grouping makes sense that way. (Poor Dinah, Jacob and Leah's daughter, never gets mentioned again after the Shechem incident.) Whether there is any further significance, I do not know, although I'm sure it has been discussed many times by the rabbis and later scholars. And regular folks sitting in Torah studies.