Hi Squeaky,
The mattress would have been fully inflated the first night as well (the latex will decompress within minutes) but your experience on a new mattress can vary from day to day and will change over the course of the first few weeks as you adjust to a new sleeping surface and the mattress breaks in. There are also some suggestions in post #2 here that may be helpful.
Outside of some of the suggestions there … the best thing to do before deciding on any changes to the mattress would be to do nothing so that you give yourself some time to get used to a new mattress and to give your experience a chance to become more consistent (so if you do decide to make any changes that it’s based on a longer term pattern of experience).
I don’t think so no.
Phoenix