It could be "phew" work stuff he left a file for someone who needed it.
It's one emoji
One emoji from an unsaved number
Surely he would save a number he is in regular contact with? He could have had a work conversation and someone at work sent a "phew" as in found it to him to let him forget about it, who knows?
OP enjoy the rest of your holiday
Perhaps have some chilled conversations saying you are feeling a bit insecure for no particular reason at the moment. See what he says, let him talk, just listen. People expose more than they like if you give them space to talk.
If he is genuinely interested in trying to make you feel more secure you will know.
If nothing else enjoy the sun, eating out, no chores, buy a book if need be, go and see something new, don't let one emoji spoil some rest and recuperation. The emoji nonsense if it is nonsense will still be there when you get home.
When you get home I would advise doing a bit more for you, find some things to do friends might grow from. You need more in your life than just him. People bounce back from losing everything in natural disasters (extreme I know) but this is one emoji, try and forget about it for now.