chasv77answered grow question 5 years ago IMO, that leaf is nothing to worry about. If indeed you just fed a little, stop and wait a couple of weeks.
If your soil is quality/rich, that will hold you for at least 4 weeks, but more like 6 weeks. Depends on your strain's ability to absorb nutes.
Since your plant is still in veg, it will grow out lots of leaves, and leave the lower ones behind, to trim, as they will be under shade.