This is on my MTB, 26" wheel, 36 spoke. I went up a curb the other day and wasn't paying attention and hit the rear HARD. The wheel is still fine, I think, and I can ride it and not know the difference. This morning though, I was inspecting it before my commute, pumping up the tires a tad, etc, and I noticed a loose spoke. It seems like the two spokes opposite of the loose spoke were VERY tight.

Can this be solved easily by someone like me who has never trued up a wheel before?