PA..
That is a little unusual so see red in seng leaves.
I have seen them of course greenish yellow, then to just yellow, and a few times very pale yellow with a pinkish tint to them.
I don't recall seeing one with as much red in it as your pic.
Probably something in the soil or just the weather (moisture levels) and soil conditions that causes that.
Not sure but that would be my guess.
TNhunter