It's probably one of the dummy reminders that comes up after a certain mileage. Pre-'18 Leafs had that.
Maybe it's what's on page 2-34 of your '18 Leaf manual? It talks about Tire and Other.
'13 Leaf SV w/premium package (owned)
'13 Leaf SV w/QC + LED & premium packages (lease over, car returned)
Please don't PM me with Leaf questions. Just post in the topic that seems most appropriate.