The weirdest contact from an ex-girlfriend.

A few years ago I had a very volatile and tumultuous relationship with a girl I'll call Sheila. It lasted about a year and a half, and ended in us "giving each other space." We chatted a couple times on the internet in the subsequent months before all communication cut off completely. I was pretty ok with this, because the relationship had been highly damaging to me, and I was really happy to not have to deal with her hurting me.

In the past few weeks, she's randomly popped into my head a couple times. Not in a remotely romantic context (I've been happily dating another woman for about a year now and couldn't be more thrilled to have her in my life), but just wondering what she's up to these days. Then, last night, I got a phone call from a number I didn't recognize (I deleted her from my phone following the breakup). When I listened to the message left on my answering machine, it consisted of about fifteen seconds of silence, and then a strangely familiar, ferally sexual moan. When I googled the area code to discover where it was from, it was from Sheila's city. Then, I googled the phone number itself, and it came up as hers.

WHAT?

So, dear Reddit, what do I do now? Should I text her or something, given the weird timing of her contact with me? Or should I just ignore it, and be happy that she's no longer a person I have to deal with?

TL;DR -- got a (possibly random) call from my ex-girlfriend, in which she moaned sexually, and hung up. What do?