Missing Mum and Dad??

Of course one of my hats is as a parent. We were only ever able to have one son - who is now 10 - even though we have been trying for abut 8 years for another without success.
Up our way it's half term week and being very fortunate, my parents are always happy to have our son with them for the holiday - they live just over 200 miles away so don't get to see him as often as they would like - win win I see it as!!
We usually meet halfway between our homes and last Saturday after the early morning swimming lesson off we went. Two and half hours later we've met up, transferred what seems like half of our house into nanny and grandad's car and said our goodbyes - see you in a week, but we'll ring every night!
Have dutifully rung each night, but due to work I missed him on Tuesday night - I didn't get home until after 9pm. Spoke to my mum who said he'd been fine. Said I'd ring again on Wednesday - ring before 6.30 as we're going out for a meal with aunts, uncles, cousins etc. OK I reply.
Make the call as instructed at 6.20 - no reply. They had already gone out. Now I was off out with a friend and didn't expect to be home before 10pm, and my mum not being too good with technology, never answers her mobile phone!!!
So I ring this morning - he answers the phone!! Hello monkey I say, I've not spoken to you for a couple of days, are you OK?
Answer - haven't you? didn't realise! I'm OK.
Now, I could take this a couple of ways really - should I be deeply crushed that my son is not bothered that I haven't spoken to him for over 48 hours or, should I be happy that he is enjoying himself so much that he hasn't realised that this amount of time has passed and that he hasn't spoken to mum? Of course I go for the second option. I know that he is safe - although my mum is usually a bit slow telling me that he has had a trip to A & E for an allergic reaction to things!! - I know that he is enjoying himself and that he is a happy and confident young man. Part of me wishes though that occasionally he would ring me and tell me that he's missing me and can't wait to come back home!!
Am counting the hours until Saturday when I'll be trundling off down the M5 to meet him half way and bring him home!!