FWIW I've always heard it described as a thundering herd. Though, your description is spot on, according to Wikipedia [1]. The problem the article discusses is called a cache stampede or dog pile [2].
It's also possible the Wikipedia article is maintained by someone with a stronger opinion about the definition than would be reflected in the typical person using the term.
[1] https://en.wikipedia.org/wiki/Thundering_herd_problem
[2] https://en.wikipedia.org/wiki/Cache_stampede
I wouldn't fault anyone for getting these similar names mixed up though.