If you were to publish a paper but you made an error in publishing the experimental protocol or parameters, what would happen to the paper? Let's say in this instance that the results of the experiments wouldn't be significantly affected. How would that process work? Would there have to be a retraction? A correction?
In most such situations there is no need for a correction. If random elements of any kind are involved then the effect of randomness might overcome small changes in parameters. You might be able to analyze that from your data.
If the system is relatively smooth then, again, small changes in inputs result in small output changes.
There are systems, however in which none of that is true. In any chaotic system (weather, for example) small changes can result in large effects.
Another factor to consider, however, is what real world effects might arise from getting it wrong. In some medical systems, say, it is important to be absolutely precise as lives may depend on results.
So, make a judgement call. If small changes result in small effects AND if there are no adverse health/societal impacts for being slightly wrong, then it can probably just slide.
You can also present your case to the publisher of your work and let them decide if a correction needs to be made.