blew out a shock?

[low 84]

my truck has been sitting for the most part the past two weeks and a little circle of fluid was forming under it slowly. i stuck my finger in it and it looked like break fluid at first so i figured a had a busted breakline. i got underneath it today to narrow down what the problem was and it looks like my shock blew out. the only thing thats wet is the lower half of the shock and where its been leaking on the lower control arm. this is a d-tech after market drop shock and its the one that is supposed to go on the amount of drop i have.

so what would cause this seal to go out? is it from sitting so long (i havn;t driven it much the past 6 months). another thing is that when i put the shocks on like 2 years ago i put the on upside down, so the canister part was on top and the smaller shaft on bottum. i didn't figure it would matter because it should still dampen the same either way. could the seal facing downwards with the fluid above it casue it to leak like that? its just wierd b/c i've had them on like that for 2 years