Fermenter Graduation

Has anyone else found problems with the graduations on their fermentation pails? I use 6.5 gallon pails from 'True Brew' like the one pictured. Currently I have 3 of them.

I'm brewing a Fat Tire clone and a Bavarian Hefe today and I just discovered that the gallon graduations on the side of the three pails are not uniform. So I did some quick math (I know, I'm a nerd) and figured out the volumes. I discovered that the graduations on one of my fermenters was correct and the other two were wrong.

Has anyone else observed this?

Brian

Yeah, I don't trust markings on the side of anything and always verify with a known measure.