Leaking valve.

[Chilli Girl]

I thought I had a slow puncture the other week so took it into my local Tyre place and they found I had a front offside leaky valve, so that was fixed but after I washed it today, I found one dust cap missing on the rear and noticed that the wheel weights inside the nearside front wheel had been moved?  Is it normal to move the weights?  I didn't have a new tyre. I also noticed that the remaining 3 dust caps were not on particularly tight as I know when I check the pressures, I always make sure they are on tight so I suspect ones worked itself off.

[Joesson]

The valve can leak if the insert is not tightened home. On the old fashioned sliding rod type pressure gauges there was a forked tooth gadget that could be used to remove or tighten them. The valve could, I suppose, possibly leak from between the valve body and the rim, but only from some impact that I doubt in the case of the OP ( @Chilli Girl )
Only if the valve was removed, and in that case the tyre would be partially removed , would there be a need to rebalance. I'm pretty sure the valve cap would not make any noticeable difference to balance .

[Chilli Girl]

Thanks Tony, it's weird I wouldn't have expected the tyre to have been taken off and you're quite correct, I haven't whacked it on anything although the potholes are awful down here!

[Joesson]

Thanks Tony, it's weird I wouldn't have expected the tyre to have been taken off and you're quite correct, I haven't whacked it on anything although the potholes are awful down here!

Maybe the valve insert was found to be loose and so the mechanic thought better to replace the valve as the existing valve is leaking for some unknown reason.