Hello and welcome to JustAnswer!
It's most likely transmission fluid. Directly above the NVLD is the power steering rack, and they often leak directly onto the NVLD. The power steering system on your van uses ATF+4, which is why it appears to be trans fluid to you.
You should be able to get by with minor seepage from the rack, but if it starts leaking fast enough or it damages the NVLD then the rack will need to be replaced.
I have owned this caravan for a little more than 3 years. I check all fluid levels when I rotate tires every 5000 miles (about every 3 months). I may have added power steering fluid once in this time frame. On 03-19-12 I was rotating tires and changing oil and I noticed the NVLD was covered in oil or transmission fluid. The power steering reservoir was not low, so I did not add any fluid.