I've noticed that the seat-tube on my 853 frame road-bike has a spot where it has visibly been filled or repaired (codged!), I bought it second-hand and have only recently put some miles on it. After a couple of longer rides (50 odd miles each) I noticed a greasy brown substance oozing out of this repaired/filled area - any ideas as to what it might be? There doesn't appear to be any cracking to the tube that I can see, just this small area about the size of a 5 pence piece which looks like painted over filler. BTW, the bike is in Bristol but I could get a photo when back home at the weekend.