unless you have recently removed/moved/knocked/unsettled the pipe they generally dont just start leaking there, 9 times out of 10 its caused by
Scrawn aka Skinny wrote:
I think you'll find the pipe is corroded and will need to be replaced.
either way its probably good insurance to replace them both at the same time as trying to get a new o ring happy with the old pipe can be tricky (aka a right pain in the arse)