Maybe she would have followed with, "Because is you are, maybe you want to..."

Slow down and make it last

Come in my mouth

Come now so you'll have time to come a second time

Fuck me first

...or maybe she was rushing the session, lol.

If there's one thing I can't stand. IS when I'm with a woman/guy and that other woman asks him *are you going to cum yet. *
It simply takes the pleasure out of the whole experience and makes her in my minds eye. Nothing more than a mechanical machine doing business. I simply can't stand those type of women.  I can see how one asking, would make a man go limp cause she just spoiled the moment.

AND YES, OP: when she asks that...she's trying to RUSH you.......her NEXT is probably waiting.

You leave out some critical pieces of information to give an honest opinion.  What was the duration of your planned visit?  Does she allow for multiples?  How was the interaction between you like?

As other respondents pointed out, there could have been several explanations as to why she asked

If she is asking "are you going to cum" or "ready to cum" 5 minutes in I would say that's a bit rushed.

Just say no!