[urq] Cooling System question

[Keith]

Evening All,
I have some curious goings-on with my quattros cooling system. On occasion but not always there are one or two drops of coolant on the garage floor. The system does indeed lose a little, but so little as to be unable to trace the source. The running temperature is absolutely normal but the cooling system remains pressurised even when the engine has cooled right down. The engine runs fine.  I have searched on line for possible causes of the system remaining pressurised, some suggest a leaking head gasket. Obviously I do not want to remove this just to look and there are no other signs that I am aware of to suggest HG failure. I will be surprised and not a little disappointed if the HG is failing because the block was Wills ringed when I built it (10yrs ago though) to ensure a good seal around each cylinder and I don;t thrash it (in fact my friend ridicule my mechanical sympathy for my car!)
I guess the question is: should I be concerned? Are there any tests I could do to confirm/deny HG failure given the current minimal outward symptoms? The amount of residual pressure in the system when cold is what concerns me the most though.
Any ideas/suggestions gratefully received (as always).
Regards
Keith

‘87 WR