Installing new planer blades doesn't always guarantee a perfectly smooth finish. Could uneven blade alignment, small chips in the cutting edge, or the wood grain be responsible? What do you usually check first?
Check if the blades are set exactly the same height across the cutterhead. Even a tiny difference leaves lines. Also inspect for tiny chips under magnification.
I usually check blade alignment first with a dial indicator, even small misalignments cause lines. Also inspect the cutterhead for debris. I've had good results with the planer blades from that shop, they stay sharp longer and produce a cleaner surface.