I pwn a 1994 Astra 1.4i. It is possible that the seals in the front brake caliper pistons are on their way out. I have made some enquiries, and I am being told that it is no longer possible to obtain seals. Instead, I have to buy the complete caliper on an exchange basis. Therefore a job which should cost about £5 (ans thats being pessimistic) is gonna potentially cost nearly £100 at best.
I find this almost unbelieveable, to be honest.