That's bad! I've been in contact with the shop where I bought them and I'm told they are rated at 10 bar max, so in theory they should be ok, but for how long I don't know! On a positive note, the lad at the shop told me they have others rated at 15bar so I'm going to get some of those to put my mind at rest.

yeah , thread tape - what a nightmare! specially the swivel push fittings which came with a pre-applied coating of teflon, bloody useless!
Used locitite 243 on all the leaking fittings and problem solved straight away. Pressurised the system and closed off the supply from the tank with no drop in pressure after 10min. Good enough for me