Looks like a puncture, but cam angle being what it is, hard to say. And it is on the rim side, so if no spokes or bad rim tape/strip. The maybe a one-off thing you might never know.

Since you've had several soon after fixing flats are you sure you aren't just getting careless and letting the tube get pinched under the tire bead as you slip the last of it over the rim?

I get that way sometimes too when I think I am too good at changing tires for anything to go wrong. Murphy steps in and humbles me.