You didn't reply to your message till now, It's too long my friend. Or you just do that because I didn't reply to your message once. You know that It was something out of my hand.
Is there anything that can be used instead of the underline part. I want to say something near to (retaliate) but that can be used in such above context. I means something carries the same idea of the word (retaliate) but not regarding to something not good.
You could say:
Or did you just do that because one time I didn't reply to your message?
Is this paybacks because once I didn't answer your message?