If you notice elasticity or plasticity of the glue, you're using too much.
The secret is using the thinnest film of glue possible. Always sand the brass and force out all excessive glue. Don't trust the hygroscopic force of the glue to create an equal film.
Use small glueclamps to keep dichros/cubes/mirrors in place, then activate.
Also, an unequal film thickness will have an unequal thermal expansion, resulting in positional drift and material stresses in the optics.