virus alert with 1-855 number then phone call

Here's what happend to my family the last 2 days and I'm curious to know what people think?

Yesterday, my wife was surfing the internet when we got a message on Safari. "Our mac had been infected by a virus and to call a 1-855 number to get rid of it" I obviously did not call the number. I looked up a solution on my phone. And as instructed, I force quit. Cleared the cookies. Hit Shift to reload Safari and all appeared well. HOWEVER... Today my wife got a phone call from 234 321-3432, someone with a heavy Indian accent asking if we had problems with our computer and volunteering to fix it for us? Obviously, my wife hung up, but it begs the question... Was the person on the phone in fact the same person responsible for the virus message on my computer? Or was this two separate unrelated attacks? It obviously would be a sophisticated and convincing scam for someone to get a message on a computer and then call the owner of the computer about that message? I've looked these scams up online. I've seen them listed separately (message on computer, phone call about supposed computer problem) but never together. My guess is that it's a coincidence for two reasons. First, the phone call scammer said he was from Windows. We have a Mac. Second, if they were already able to infiltrate my computer to the point where they knew my phone number, why call me about it to get on my computer again? Any experts out there with any other theories, I'd appreciate it....