All the comments saying to confess and explain are only valid if salvaging parts that are going to recycling is an acceptable practice to begin with. Based on OP's reaction, I'm guessing he shouldn't be "salvaging" these parts at all.

Yeah, I get what you're saying but I run into family friends all the time when out with my family. I have kids and am involved with the community though, so it's not a rare coincidence for me, it's very much the norm. But running into someone 3 hours away would be a pleasant surprise.

I'm not sure this warrants an explanation? They were only half an hour away. I'd find it quite reasonable to run into family friends if I'm out and about only 30 mins away. Maybe if they went out somewhere 3 hours away it'd seem weird but the chances of running into friends of the family 30 mins away from home can be pretty high. Higher if your family is out-going and makes a lot of friends.