I've been networking for many years. Belong to a couple of referral groups, have done presentations to the groups, and the whole bit - and I still sometimes get tongue tied. I get in a hurry, forget to prepare my 30 second for THAT particular meeting, forget the story I was going to tell and who's going to make a good referral for me that week - and just completely blow it. About a month ago I forgot my company name and stumbled all over it. LOL...Yikes!!!
It happens. I've seen people who I consider the kings & queens of networking blow it. The key is just what Shandon mentions....laugh it off. Laugh at yourself and others will laugh along with you vs. at you.
It also works that they see you are human and obviously you handled it and recovered it beautifully or you wouldn't have had people asking you for your card and showing interest! Just don't let it discourage you at all if they showed interest and now don't call. Just remember the 7 times rule. You made contact...now take it home by doing all the other marketing stuff you need to do.
Best of everything!!!