Board Thread:Questions and Answers/@comment-24926745-20160214213230/@comment-27701762-20160215065450

So I did some experimentation on a fresh-ish file (I had saved the game at the Mettaton Hotel to save time), as I'd never fought Asgore multiple times on the same file.

Defeating Asgore the first time triggered the usual events. I killed Flowey in order to recreate that particular condition.

Defeating Asgore the second time triggered a line from Flowey about how killing him solves nothing, since as long as you reload the game he will come back and take away your happy ending (I had spared Asgore here, so the line might be different if you decide to kill Asgore). As was to be expected, the Omega Flowey fight does not trigger.

Defeating Asgore the third time triggered a line from Flowey that went roughly "let's get this over with." Again, no Omega Flowey fight.

Defeating Asgore the fourth time triggered the "..." line you are speaking of.

So neither skipping the Omega Flowey fight nor the dialogue line are a glitch in themselves. The only way getting that particular dialogue line would be a glitch is if you received it prior to your fourth fight with Asgore (i.e. before completing the Neutral Route three times without a True Reset). If you received the line under these conditions, then it was likely a glitch, though someone else might have more information on what triggers the line.