If you saw a few dollars show up in your Steam Wallet unexpectedly over the past few days, don't sweat it, you aren't being targeted by scammers looking to fleece you or get you in trouble with Valve and someone hasn't sent you funds to try and hide them away somewhere - it was actually Valve that sent it do you.
Reports of the money showing up in people's accounts began a couple of days ago, with the payee stated as "Valve Mastercard," which sounds official and therefore just a little fishy.
However Valve has now gotten in touch with several of the concerned affected and has explained the situation. They all purchased a Dark Souls III, Steam Controller bundle, which should have had a small discount applied. For some, it didn't work, so Valve was merely retroactively applying it, by sending them a small rebate.
This seems like another instance though, of Valve's lacking communication causing unnecessary concern. Were Valve to have gotten in touch with people sooner, it might have caused less worry among users.
Instead they had to chase things up themselves.
As much as Valve is a well beloved company, it continues to operate quite often in the dark, which in today's world of much more connected companies, seems a little obtuse.