I walked by a coughing toddler with her mom saying "i hope she didn't get chicken pox." if this toddler had been exposed, should i get vaccinated?

No: Even if child was exposed, walking by them is not enough exposure to get vaccinated. Getting the vaccine is not a bad idea if your blood work is done and your physician finds that you are not immune

Curious question: I would not look at coughing as a early feature of Cpx, so many other things would be more likely, but still would be possible. From exposure to first contagious point is 8-9 days. Most adults are immune to Cpx, even those that don't remember having it. (96%), if you are sure you never had it, having the vaccine now would protect you and any pregnancy later. Blood work could confirm you are immun