Being a mother and grandmother, when traveling you should always carry a changing pad or blanket that can be put on a surface to change a baby....and NEVER in an area where food is served. That is disgusting, but also against health code. The bathroom is the appropriate place for this to take place and I am surprised that the mom was not directed there.

I would definitely send an email to them - it will be a reminder for them to be more diligent in the future!