Take it back to the transmission shop that diagnosed it and did the repair. Without knowing the code, it's impossible to know.

My moms pilot did the same thing, it went away eventually and then they traded it in. She also did 40K on a conventional oil change, so yeah. As far as I know flashing D is a transmission fault. 

Hello, I'm driving a 2009 Honda Accord. One day the d4 starts blinking so I take it to a transmission shop. The replaced the solenoid that was causing rough shifting from 1st gear to 2nd. I was driving home and its definitely shifting better. But near home, it starts blinking again. Any ideas? Thanks.

D4 blinking and CEL on, solenoid already replaced