My guess is that if there were going to be real hostilities, you'd already be seeing them. Remember the old rule: no blood, no foul. Even though neutered, they still have to work out the dominance, and it only prolongs the process to interfere when not absolutely necessary. If you catch them cuddling, then even if they are noisy at other times, it's okay.
If you start seeing fluffing up, arched backs, sidling (one rat moving his butt sideways into the other), that sort of thing, you might want to consider intervening. If they tussle, observe what the aggressor's goal is. If it's the neck, it's not serious antagonism; if the butt, keep a sharp eye out (that could be possible hostility, not just dominance). There may be noise and there may be squeaking; this is normal. Sometimes holding the two simultaneously can help, because it sends the message that you, the true alpha, consider both of them part of the mischief. Vanilla on the neck and the rump (a small drop in each place) is supposed to help, though I've not seen it make a clear difference. If they didn't lick the honey off each other, then smearing them with yoghurt isn't likely to work either.
Stressful experiences they could share would be a car ride in the same carrier, over a twisty, bumpy route with the radio fairly high. Or time together in the tub with only a small island for them to take refuge on together as the water rises.
