You did not
over react, and you did
do the right thing. It's always good to listen to your gut, and equally good to get away from trouble before it starts.
Maybe nothing happened because the would-be criminals realized you'd picked up on their plan. Or maybe nothing happened because nothing was going to happen. Does it matter, really? In either case, you did the right thing by listening to your gut and quietly leaving the situation.
A lot of people are so enslaved to looking cool that they put themselves and their loved ones at unnecessary risk of dying of embarrassment
. For example, I had a friend who was sitting in a restaurant when the smoke alarms began to sound. He did not get up and leave --
simply because no one else did, and he didn't want to look like a coward or a fool. He looked a great deal more foolish ten minutes later, when the fire engines arrived and the fire marshall yelled at everyone who'd remained (and esp. at the manager) for being a bunch of damn fools too cool to heed an alarm system designed to keep them safe.
Listen to your alarm system. That's what it's for.