I remember something in the 'news' saying that cash donations were coming in so fast for obama that they 'couldn't trace' WHERE all donations were coming from.

It was either last year or earlier this year when someone was looking into campaign contributions from political orgs (eg Act Blue) where hundreds of small dollar donations were on record as coming from the same person(s). They would find these people and interview them and it would be some senior and they would ask, Did you really make $75,000 in donations last year to whoever. They would laugh and say, Heck no, I don't know where that came from. That's more than I make in an entire year.

So no that doesn't surprise that they "couldn't trace" where the money was coming from. Probably happens way more than we know.