I've found over the years and with many different barrels, that they are not all the same and they have their quirks.
I wouldn't worry about it unless it is something that continues to repeat after using the same ammo.
To put your mind at ease, you can do a good cleaning of the barrel, and use the ammo that you intend on using and after firing a few fouling shots, then shoot for groups, and stay with that ammo until your satisfied that the barrel has settled in.
Just remember that not all barrels are the same, and what one barrel likes, other barrels may not, and once you find what works in yours, just stay with it, and you'll be a lot happier that way.