Wife and I were discussing my last tetanus shot. We remember what I'd done that required it ... but not how long ago. Within ten years, which is the length of time we think it needs to be boosted.
On the other hand, this was a nearly new barrel, still had a little of the synthetic oil it came with. No rusted parts, and the metal edges that cut me were brand new exposed metal.
I'm pretty sure I'm good. If I start stiffening up, experiencing unusual spasms or getting lockjaw, then I'll know I was wrong.