What could cause intermittent start failure when engine is hot?

My 2018 440i (F33) suddenly has an intermittent starting issue. It starts fine almost every time, but occasionally the engine will turn over very slowly and fail to start. On the next try - within a few seconds of the non-start - it fires up normally. This only happens when the engine is hot. The battery is as old as the car and shows good voltage. Any thoughts on what might be going on? Thank you.