First, I can't condone what they did.
You handled it well and it sounds like your response made them more understanding as well. An antagonistic response or going straight to HR and reporting them would likely have made them less sensitive and more bitter.
I really really like what Flybye said.
There's a line in Schindler's List that I particularly like...it goes something like this:
"Real power is having the ability to do something (go to HR) and choosing not to actually do it"
If you don't grow where you're planted, you'll never BLOOM - Will Rogers