The threshold for a bonus unit is currently 10 SP, so a 1 SP delegation would have been ignored. Even if it was registered, if 1 unit earns an estimated 0.0095 per week, then 0.1 would earn 0.00095 per week, which would not be enough impact on your upvotes for you to ever see it.

Our new system will reward more for delegation, but the minimum threshold would still be 2 SP.