Meanwhile, asked if he thinks Miley - who recently rekindled her romance with ex Liam Hemsworth - would have remembered their first kiss, he told BBC Radio 1: "I don't know. I'd have to ask her. But I'm sure she does. It was probably pretty potent."
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The Jealous hitmaker doesn't have any "regrets" about his past relationships despite being really young when he first met Miley and previously said he was grateful for her friendship whilst they were both growing up in the spotlight.
He previously said: "I was so young. What's unfortunate is that, as we got older, we ran in different circles. We've always had respect and wished the best for each other. I don't know that I have any regrets. It's more gratitude for having had a good friend in a time of craziness in my life and in hers."
- Bang! Showbiz