Thanks for all your replies folks. Been a busy couple of weeks, none of it PCa related.
Anyway we are just going to have to sit it out and wait another 3 months for a retest. Or maybe 2 if hubby can persuade Mr P to write a request sooner.
For info hubby has his tests done privately at the Spire in Leeds as the local NHS test only goes to <0.01 whereas Spire go down to <0.003
Spire now send all of their samples from all hospitals to a central lab, (in Cambridge I believe) so not to the local NHS hospital in Leeds that Lynn talks about. This used to be the case but not any more.
There is still an amount of error inherent to the test, whether this latest increase is a signal or noise, only time will tell