What happened?

[Virginia Hunter]

I hunted Monday morning and the thunder began so I got down. It was dark when I was lowering my bow and it hit the ground hard enough to pop my quiver off. I was worried I messed something up so I shot it. It was dead on at 20 but it droped almost a foot at 30. I have a Savage pendulum on my bow and when it was sighted in it was dead on at 20 and 2 inches low at 30. Do any of you have any Idea of what could have happened?

[thenuge15]

did you only shot at 30 once? if you only shot once maybe it was a bad shot.

[Virginia Hunter]

no, I took several shots at 30 and they were all in the same spot.