we increased our colony by getting gliders usually in groups of two. And it
definitely seemed like one was always much more outgoing and curious. while the
other was reserved and would stay in cage and watch from the back, run from your
hissing can be a sign of a UTI, we got a single that would hiss when he peed,
but a visit to the vet and the vet said he appeared to be very healthy, the hissing
could be a habit he picked up from a past UTI or just something he did. we have
had him a few years, and I don't hear him hiss anymore.
So my thought was when your second glider got on you, it was time for the
dominant glider to mark you as theirs and gave a hiss as he peed.
Our dominant male used to mark me alot as soon as he got out of cage and on my
arm, even if he had been awake and running around cage for awhile, he seemed to
always save me a few drops, put he seems to do that a lot less.
sounds like your bonding is going great.