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Now everyone has come out with their pet peeves, so here's mine: I owe you a debt of gratitude.
Doesn't "debt" mean that something is owed? So owing a debt is redundant. It sounds like you are owing to owe someone, i.e. putting it off. You need to thank them, but it's like you're too busy, you're going to get around to thanking them someday but not right now. Then, at some point in the future you will acknowledge your actual debt, not just "owe" them the debt. Sometime after that, I suppose you will be able to thank them.
Just say thank you! Say it right now!