Not me but one I can remember from a ASR report.
During the decent the hold smoke warning went off stayed on for 30secs then canceled, on finals it went off again.
Emergency declared landed no probs, couldn't reproduce on the ground until the engineer took a call in the hold. Where apon the smoke alarm was triggered until he finished the call. It was presumed one of the pax had left thier phone on in a bag. There was no previous with this aircraft for surious alerts and neither was thier after.
They reckon it was some sort of ionising thing going on with the detector.