Hey I had Shingles twice! (And I'm only 26 years old, had chicken pox as a kid, and the doctors were soooo
confused. Then they explained to me that as children are being vaccinated for varicella, chicken pox isn't widely in circulation anymore and you need minor exposures to it throughout life to keep the virus dormant, otherwise it flares into shingles under stressful and low-immune system periods. Growl.
However, my youngest daughter was not vaccinated for Varicella and she did not get chicken pox from my Shingles, and we were in very close contact as she was just 9 months old when I got them the first time. So I don't think it's likely that your kids will get chicken pox from your Shingley coworker.