you sure you didn't use baby johnsons or homebrand?
Most good brands should be fine as they usually say they don't thicken or thin under cold or hot conditions on the bottle so should be ok if it was fresh and sealed in the bottle... you could have built them wrong? If your still unsure just redo the shocks again with new oil if they really do feel bad so then you can be 100% sure whether it's the oil or just you
