When are memory issues something to worry about?

[SafeToCross]

For a while now, DH, 50, has seemed to not recall arrangements or things we had discussed - fine, I thought, just slightly tuned out of family life after a busy day at work, pretending to listen but really his attention is elsewhere. Yesterday, we were in the car together when I got a phonecall with a quote for something we are purchasing. I told him the details, he was annoyed at the price, but then agreed it was about right. We mutually agreed which of the price points to go with. (Full 1:1 conversation, no distractions, except he was driving I suppose). Then today he asked me 'did you hear back about that quote?' I waited 30secs to see if he realised his mistake, he then said 'how much was it again?' obviously realising we had discussed it but not remembering. He's not particularly stressed I don't think, doesn't drink much, not on medication, pretty healthy. It's just normal, right? Or something to be a teeny bit concerned by?