EPiServer Find 429 Too many requests on a cached method

Hi,

A customers site that I'm working on is getting error (429): Too many requests once in a while. A simple way to allways re-create the error is to hold "enterkey" on the search function. The search basicly does this:

var result = searchHits.StaticallyCacheFor(TimeSpan.FromMinutes(5))
                                                    .GetResult();

 The error: 

The request:

I could make a timeout on the search in javascript to prevent someone from holding enter, but I'm confused about why we get a 429 when the query is supposed to be cached?

Sincerly
Salmin