I haven’t heard the Chirping myself but have been told of it before – if fact – Hedgehog Bottom has a little library of hedgehog communications and what they mean:
The Chirping they have captured put this down to contented hoglet noises coming from a nest.
On the possibility of a juvenile female front – I have to say – the males will tend to try their luck with any age female at this time of they year, so perhaps he hadn’t noticed her (if she is a female).
I have become aware of the fact that because hogs rely on their sense of smell so much – you can get much closer to them if standing down wind of them (and quietly to observe). I wonder if your experience above is similarly related in that the male hadn’t noticed because of the wind direction at the time?
Lovely to have another visitor to your garden anyway – and skittishness being a good habit to have developed in terms of life survival I expect – or certainly avoidance of humans if at all possible.