How does DNS "get stuck"?

I recently registered a domain and got hosting from Dreamhost. But when even after three days, the website was not accessible, I contacted support about it. This is the response the support person gave me:

"My apologies! The DNS had gotten stuck, so I went ahead and pushed that through for you. Please allow 2-3 hours for the DNS to propagate."

Now I have to say that my knowledge regarding these things is virtually zero, and I couldn't understand what the support person meant, so I ran a search and it seemed that Mr. Google knew just as much as I did regarding this.

Can someone tell me what "dns getting stuck" means?

Probably it means the changes weren't propagating from the master server to the slave servers.

In many high-intensity DNS environments, changes are made on a restricted server not actually serving end-users, then replicated out to the actual client-facing DNS servers. Sometimes these changes aren't replicated successfully...

"DNS Getting Stuck" means that the support person you talked to is clueless.

In all likelihood, the record was probably never entered into their DNS servers or the DNS process was hung and needed rebooting. Remember that next to ISPs, web hosts tend to have the least competent front-line staff and have seared consciences when it comes to lying. If you had a dollar, they'd steal two from you and make an auto-renewal to do it again in a year. </rant>

Sounds like a generic error that a support rep might give for a typo. If forced to guess I'd suggest someone updated the zone file but forgot to update the serial and the new details were not loaded by the server.