Halfshaft (grease on boot)?

Shouldn't be greasy. You should inspect for any holes or tears. If no holes, or tears... Maybe grease left from factory?

 

Grease on the outside of the CV Joint Boot "usually" means it's punctured, cracked or the band clamps have become lose or broken. If this is the case, a repair kit is available. If the problem is not addressed it will lead to premature failure of the joint from lack of lube. Thorough inspection will determine the cause.

 

I doubt that the warranty will cover a hole in a CV joint boot after 10k miles.

 

I hope so at 10,100 miles. Good catch.

 

It doesn't cover road hazards.

 

Are you sure it's grease, my right hand inner CV boot has had from new, a thin coat of sticky residue all over it (looks a bit like the protective waxy stuff they spray on metals to prevent corrosion) but it's definitely not grease and there are no leaks.
If yours is leaking there will be some grease deposited around the area where it gets flung off the boot.

 

^ +1.

I was thinking ours was leaking or something. It looked shiny, but I think now it was just some coating left over from manufacturing process, or whatever. No change in over a year since. No sign of leaking/flung grease.

 

I wouldn't worry about it, mine's not showing any adverse effects after being like that for 3 years

 

If you don't see any evidence of it throwing grease in surrounding area, I wouldn't worry about it.