Dell's claim sounds like rubbish to me - are you sure that you were speaking to someone who knew what they (and you) were talking about.
Admittedly the name of the partition sounds a little fishy, but that aside, all Dell servers installed using their server assistant CD will have a hidden "utility partition", which will be FAT32. Heck, it's even documented.
I suspect that's what you've encountered, and that the partition name was changed by something like an imaging tool (or do you run a homebrew post-install script to name partitions on your servers?) that just names the first partition "OS" without checking if it actually does contain the OS first.