Lemons getting red spots..

latoyaaaa

So we have a lemon tree out the back of our new rental
First thoughts: yes! I don't have to buy lemons, there expensive at the moment
So I picked some ripe ones
I haven't gotten around to eating them straight away
After two days I noticed they are all covered in red spots
I cut one open to see if there's something wrong and they are perfect looking inside
None on the tree and the tree itself doesn't have spots..
Can anyone explain why this is happening?

It was 6 lemons in total that I picked not only a few