My mentor at work stopped replying to my messages three weeks ago and I keep assuming it's something I did

We used to have a standing 20-minute chat every other Friday. She's senior, genuinely good at explaining things, and it was the one part of this job that made me feel like I was actually improving. Then it just stopped — no cancellation, no "let's reschedule," just silence. I know rationally she's probably swamped with her own deadlines, but my brain keeps running through the last few messages I sent looking for the thing that made her check out. Do I just ask directly, or is chasing a mentor for time a bad look this early in?