I have a problem with my teacher (AS)

So- i've just done a geography mock, and I've got Unit 1 back- i got an A. I am SO worried, because I think my teacher marks WAY too generously- like, for one question; why does the UK's ageing population bring many economic challenges.

I wrote:
This is because the ageing population may bring a strain on the healthcare services required to maintain their health, e.g. the NHS in the UK. In addition, the economy would begin to go in decline as there are increasingly more numbers of over 65s, thus, more pensions must be paid.
Also, another economic impact is the fact that more money is required for care homes to function, as extended families are less likely to live together now.

Mark scheme says:
- fewer working people paying contributions currently than dependnts making demands
-may quote examples, e.g. NHS care
-may have data, e.g. no of 16s is less than no.of over 65s
-may provide life expectancy data and makes links with rising costs treating dementia, etc.

1 mark for each basic idea, 1 mark for each extension

nb: this question is 5 marks, i got 4/5- i think this is TOO generous- what do you think? thanks. (((

I think you deserve 4/5.
Mark scheme:
'May quote examples, e.g. NHS care':
Your response:
"This is because the ageing population may bring a strain on the healthcare services required to maintain their health, e.g. the NHS in the UK."
The mark scheme is asking for a reason, with a quoted example - which you have done: you've given the basic idea of healthcare strain, and extended it with required to maintain their health and an example. 2 marks for that bit.
Mark scheme:
'fewer working people paying contributions currently than dependents making demands'
Your response:
"the economy would begin to go in decline as there are increasingly more numbers of over 65s, thus, more pensions must be paid."
Here, you have stated that more pensions must be paid, which obviously means they are not paying contributions. You only made a basic point here, and didn't go into detail: 1 mark.
Your response:
"another economic impact is the fact that more money is required for care homes to function, as extended families are less likely to live together now."
I understand it's not exactly on the mark scheme, but here you have made a basic point about how families will not live with their extended family, but will need treatment; it hasn't been extended though, so 1 mark.

If you're still concerned, just go ask your teacher why they gave you those marks and have them explain it to you.