Likely just a bit larger extreme spread than perfect combined with small powder charge changes and a small sample size. I jump up to a grain or two between stops for bigger cases and don't worry much about anything but the target to start with; I've got some loads I have been loading for better than a year that haven't been chrono'd yet but they shoot just fine in any condition.
High pressure can cause big extreme variation numbers, especially when the bolt lets loose; pretty quick pressure drop off then and you'll have a big x for that group. Kidding on that one, sort of.
Much more of a safety and caring for your equipment issue, but your accuracy and uniformity can go to pot with too much pressure for sure.
The easiest pressure measurement system I've seen yet is the shoe test; take off your shoe and tap the bolt open with it. If it doesn't go easily in a tap or two, you are likely over pressure.
A 10 fps x with a 3 moa group is still a 3 moa group.