I regularly get condensation in the window from sweat. Also, just after the pod change, there can be some insulin left from priming that causes a bit of “condensation”. To test for leaking, I run my finger over the adhesive on the cannula end. If it smells like insulin it is a leak, if not it is probably just sweat.
I had a couple of boxes of pods about 9 months ago where the adhesive was not very good. I ended up with some leaks (caused by cannula movement) and pods not sticking for all three days. I have not had adhesive problems since I finished those boxes off. In fact the PODs now stick really really really well. I just clean the site with alcohol, wait for the alcohol to dry, and stick the POD on. Some PODs are so sticky that I have to use alcohol (or something stronger) to remove the adhesive.