Are rain checks a polite rejection?

Anonymous
Woman that I have been dealing with (coffee meet-ups and drinks - which she initiated) then we hung out based on me asking - which she extended from just drinks to hanging out more and getting food has recently become less receptive to hanging out.

I asked her if she wanted to go out later, and told me she already had plans for that week, so I said no problem we'll see about the week after.

Texted her two weeks later and asked if she wanted to go out again, and got a reply two days later saying she's sorry for replying so late, but she's been busy with all her projects for her work for now, but hopes to be done with it all in a few weeks, and she'll take a rain check.

Should I assume she's now not interested anymore? I've left the ball in her court now by telling her to contact me when she's free and we'll try to set something up.
Are rain checks a polite rejection?
3 Opinion