It was a known problem on these vehicles and is not mileage-related. It is also not a warranty issue.

Ford did actually modify the slave cylinder in the gearbox though, and when retrofitting for the first time, you should also fit a modified pipe from the clutch master (although most of the time you can just bend the pipe slightly).

Seems to work either way.

My old R-reg 1.25 Fiesta had a whining clutch release which died about 35k (owned it from 26k) and had a modified one fitted in its place which was still going when I sold it with 83k on the clock. I also have a X-reg 1.25 Fiesta with the modified bearing as standard and that has never whined yet and has done 29k from new (owned it from new so can verify it all).

Modified release bearing = 1075776
Modified pipe (Fiesta and Puma models, not Zetec-S 1.6) = 1095276
Modified pipe (Fiesta Zetec-S 1.6) = 1105378
Modified pipe (Ka) = 1131246, superseded to 1144461

Hope this helps.