That is probably one of the very worst things you could do. Do you have any idea how much dirt and crap that stirs up in the bottom of that tank? If the pumps are well maintained, they do have filters installed.....but, we all know filters do not catch everything.

Most recommendations that I have seen suggest waiting at least 1 hour after the tanker drops fuel before you fill up (if you happen to know exactly when that is). I would never, ever get gas while a tanker is dumping fuel....but that's just me.