Leaks rarely "fix themselves", although it can happen it there is water involved.
If these are compression joints with metal ferrules, there is a certain "touch/feel" involved. Broad rule of thumb is hand tight, then one half to at most one full wrench turn. A 1" fitting feels different than a 3/8" fitting. Unless you were really wimpy on first install, retightening may not help. You could try and additional one quarter turrn. But overtightening is a real problem which damages the tubing.
Pressure will change with temp, but you said the soap test reveals bubbles, and that is not good.
The issue is based on Boyle's law, Charles' Law, and probably Avogadro's number. This is the combined gas law equation:
Combined Gas Law:
Gas Equation: P[SUB]i[/SUB]V[SUB]i[/SUB]/T[SUB]i[/SUB] = P[SUB]f[/SUB]V[SUB]f[/SUB]/T[SUB]f
[/SUB]
where i is the initial numbers, and f are the final numbers. You can see that with volume constant, if the Temp changes, the pressure changes proportionately.
Why so many compression fittings?