that's a sign your clutch is starting to wear out. you didn't mention how many miles you have on the car. and that model is one guys will beat the crap out of because its the AWD sports package. One thing you can do is when the clutch finally goes out and you need to replace it you should look into getting a stronger aftermarket clutch. 

Is this just a daily driver for you?  

I'd bleed the system.  You losing fluid?  I've found this a first symptom of the clutch master cylinder going bad but air in the lines can cause this too, hence recommendation on bleeding the system.

Sponginess is a clear sign of air or a gaseous fluid in the lines. maybe water which becomes vapor when engine is warmed up.

DOT hydraulic fluids accumulate moistur from the air over time. you might want to drain and flush it with new fluid before the water starts corroding a more expensive part. Check your owners manual there should be a section that recommends fluid replacements for every X-k miles or X years.

cheers,