‘Liking’ his ex’s photos

So I noticed he liked a photo of his ex’s dog on insta.. wasn’t to bothered by that but carried on scrolling and realised he’s liked pretty much every single photo of hers! Even her holiday bikini photos and selfies. 🤔🤔 Am I being over sensitive or should I be worried? FYI they were together for 4 years but split up over 3 years ago. We’ve been together for just over a year now.

He’s also got printed photos of them on holiday and even ones in bed together. I know everyone likes to look back at their memories but is this too much? He doesn’t know that I know he has these photos hidden in a draw. Should I confront him or let it slide?