Let's pile on the mods!
Seriously though, mods don't always have time to send messages to people asking them to follow the rules. That would be a full-time job, given the number of people and posts on this entire site. It's a lot easier for each member to read the rules and follow them, than for a handful of mods to police thousands of members.
That being said, I have no idea about your ad, as I didn't lock it. But, 72 hours should be 72 hours, regardless of what time zone you are in, right? If you post from there and bump from there after 72 hours, there should not be an issue.
EDIT: In honor of this thread, I just sent a PM to a member telling him about the bump rule. I deleted his bump, but did not lock or otherwise penalize his thread.