That long ago, then I cannot imagine it is still Nixx poisoning... so you're probably good.
And perhaps the "mucous" was just a nervous snake being startled and spitting up some water.
As you keep an eye on her, you should be able to get a feel for what is going on with her. RIs aren't hard to spot, esp. if they are at that stage. Best to watch her water dish...
Fingers crossed for you.
Bruce