Occasionally leaking tap

[werth]

Hi!

I recently replaced my shower mixer tap, but it has started to leak occasionally. It only seems to happen at night. When we close it in the evening, everything is fine, but then a few hours later it starts leaking.
The tap is a bit stiff, so I suspect that it may not have been closed all the way, but I still don't understand why it only starts leaking later on.

Any advice is appreciated.

 

[Exedon]

I take it it's dripping through the shower head not a leak on connecting pipework?
What type of system tank feed or pressurise/combi?
If latter ive seen taps & shower valves pass later in evening as water pressure rises

 

[werth]

Yes, it drips through the tap, not pipework.
I've got a combi boiler.

Any way to prevent this?