On the lips...
Well, there you go... It's not rocket science, he's into you :)
I honestly think humanity was far much better a century ago! without mobile phones LOL!
You know, for shy people it may be easier to text sth rather than say it in person. Do you tell/write him things like "I really had a great time today/last night :-)", "Thank you for a wonderful evening :-*", etc? When you write sth like that use this opportunity to send him some "kisses" :)
Btw, Myself, I forgot to mention something. If you grew up in Italy you may be in for a culture shock as far as Polish guys' behaviour towards women is concerned just as I was when I was in Italy. Italian guys are far more straightforward. I was much younger when I visited Italy and I remember how surprised I was when two guys just came up out of nowhere to me and my female friend on Piazza San Marco in Venice and asked us out for a coffee lol We were like: "Is this normal? :O" ;D I was so suspicious of such behaviour that I even thought that they might be working with human traffickers in order to lure some naive tourists because there were so many stories of human trafficking of Polish women and girls in the West that I was really wary. I almost had to drag my friend away from them because she was willing to go with them, I hope she didn't hate me for that ;D
Or those packs of young men/boys yelling after us - for me it was pretty intimidating and the further you went away the louder (and more angry?) they were - I wasn't sure whether they were hitting on us or whether they wanted to kill us ;D o_O
So, since he's not Italian, I'm afraid you'll have to embolden him a bit :)
Maybe when you two meet after the holiday greet him with "Hi, I missed you!" and give him a quick kiss on the cheek and a big smile :) And, as I said, cut the physical distance between you two, when you're walking, walk near him, take his arm, use some opportunities to touch his arm, back... Like when you're going to prepare a meal together, for example, tell him to chop the veggies or whatever and check at some point how he's doing, ask him in a joking way if he's managing and at the same time touch his back or lean on his shoulder - sth like this:
When you're going to watch a film sit close to him and not 5 meters away :). When you're going to comment on some scene in a film lean a bit closer towards him than you normally would, maybe gently touch his arm...
You know, that's basic stuff so I think he should be able to notice all those gestures and interpret them in the right way...
And if he kisses you again, return the kiss - so he wouldn't have any more doubts about whether you liked/wanted it or not :)