Singlespeed & Fixed Gear - Bleeding Rust

I just got home after some hub trouble. After feeling the cranks skip, like when the a lock ring is loose, i took a look at my wheel. I have been riding it hard for about for months since installing a new cog. I figured that whatever happened, I could just flip the wheel around and use my other cog. I rode slowly home, because I didn't want to flip the wheel while it was covered in grime, it is really slushy here. For a little while I felt a slight vibration in the wheel. When I got home, the slush on the NONdrive side of the hub was completely orange. I'll take it apart after it melts away, but I dont know what happened. These are sealed hubs.

i am not really going to speculate on the origin of your particular problem, but 'sealed hub' really doesn't necessarily mean a damn thing in terms of actually providing weather sealing. sealed is just misinformed shorthand, a lot of the time, for cartridge bearings as opposed to a loose ball setup. loose balls can be very well sealed inside a hub, and cartridge bearings can have amazing seals. cartridge != sealed, and, loose != unsealed.

quick rant.

Yeah, I figure the cartridge seal broke, but I don't know what it has to do with the slipping. Perhaps just coincidence.

The seal is probably still ok. Cartridge seals alone are pretty useless against water. If the hub just uses the cartridge seals with no additional sealing then wet weather can cause problems. Mud and slush are worse as they can stop water from draining off and hold it against the bearing seals.

Also some manufactures just use off the shelf bearings that have a small amount of thin lube, presumably because they are intended for use at high speed in dry environments like at the ends of an electric motor spindle.
If the seals get wet the bearings quickly end up with a mix of water and lube. Good thick grease is much better at keeping water out.

It also might be worth occasionally prying the seals out of the bearing cartridges to clean and grease the bearings, a grease gun makes this quick and easy. Occasional maintenance can increase the life of the bearing by quite a bit.

There are alos a lot of "sealed" hubs that are loose ball. They have a metal or plastic cap pressed into the hub body and a rubber lip seal on the cone.
Either way you need to take it apart, clean everything and see what shape it is in. If cartridge you might luck out and just regrease if they are not to rough. Otherwise knock em out and replace them. If they are loose ball go ahead and put new balls in.