Dead slave cylinder or just air bubble?

[Thieu]

So last thursday I get in my car after work and the clutch pedal is almost to the floor... doh...

I pop the hood.... the fluid is about an inch low... but nothing leaking around the master cylinder. I check under the car and check the slave. It's wet. So I buy a new slave cylinder and get some fluid. By the way... tried to get a speed bleeder but need a M7x1.0 which is impossible to find... so I forgot about that for now.

Well I filled the fluid up to the proper level and haven't had any problems. Nothing is leaking and the pedal feels better than ever (I removed my damper awhile back, which might have left a bubble of two in the system).

So do you think I should go ahead and replace the slave even though it's working fine or it might have been a bubble that passed through the system and exited at the slave?