You're doing worse than average, but not much worse if you have 25mm wide tires. These tires have very little volume, and so the normal blled that happens through the tubes walls, has a bigger effect on these in comparison with a wider tire.

I ride tubulars, and topping off the tires is the first part of every day's ride. Also consider that if you use a tire gauge, there's a good chance you're losing 5 or more psi every time you take a reading.

OTOH- there may be a problem, test to valves by putting a drop of water (spit) on each and watching for bubbles. But in all fairness I suspect that you won't find anything. If one tire loses pressure faster than the other, it's a leak of some kind, but if both tires lose pressure, it'smost likely normal bleed, since the odds of two tires having the same slow leak are too low.

BTW- if you're planning a long tour, get a reliable full length pump, and get used to using it. Flats are too common, and the chore of topping off will make you miserable unless you have a good pump.