I would bet that most of the conversion happened by 20 minutes, with a temp of 154. I've had more than one mash show complete conversion by 20 minutes, when mashed in the mid 150s.
I wouldn't worry about it at all. The only thing you may notice, if anything at all, is that it may finish a bit drier than you intended and may have a bit thinner body to the final beer. All in all, probably good things in an IPA anyway!
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