We have seen this problem just recently on two gels poured from the same solution (Long Ranger) on the same day. It did not happen on subsiquent days, so I figured it was a glitch. My tech may have done "something" but does not remember if he did anything unusual or if some unusual event occured during the pour. I did't think at first that it was sample related we have such a vast variety of samples on our gels, individual labs do their own reactions....DNA sequencing anarchy. However, I did notice that the samples on both of these gels gave particularly strong signals or rather consistanly strong (unusual for us) across the gels. Since it had not happened again I had not thought about it until I saw your post.
I wonder if it has to do with the total amount of DNA on the gel.
Has anyone tried to "over load"a gel to see what happens?
Steve
Stephen A. Bobin
Manager
Molecular Biology Core Facility
Dartmouth College
Hanover, NH 03755
603-650-6546