Were you riding hookless or rims with a bead?
a tire shouldn't burp if it is matched well with the rim. It really needs a good bead seat in the rim bed. If it is matched well, you can ride the tire when it is flat, much like you can a tubular tire.
But like Koyote says, it happens. There are no real standards for gravel tires and wheels. I have some "smallish" diameter rims and some non super tight tires and they are super easy to mount. I also have some super tight beads and some slightly oversized rims, and they won't mount at all. Tire/wheel interface is a **** show.
In your case (with a loose or uncertain bead set), I use something called "skinny strippers." Basically a latex rim strip, but it bonds to the tire in essence making the tire kind of a tubular tire. The tire will hold (a little) air even when off the bike. So burping is basically impossible. But, if you have a well matched tire/rim combo you shouldn't need anything like that.
And for gosh sakes, don't slow down!