Something been making my puzzler sore for some time..........

I post and read from both home and work.
If I read a post from - oh lets make up a name - Tam Brassiere - that has one reply from Divine Hell I see both posts.
If later in the day I revisit that thread - which by now has more posts from FinkC, heBlonesome and ten more each from Divine and Tam, clicking on a message I have not read will show me a full listing of the thread at the bottom.
Clicking on the original Tam post will only show those 2 first posts - I guess by my browser cache.

But, if I go home and look at that thread (which has by now had input from Tiny, Scutt, MaryJuana, philmacavity and 20 more from Tam and D. Hell) by clicking on the first post again - I still only see those 2 first posts.
This suggests more than just browser caching going on.

Are you surreptitiously tracking our IPs with posting/viewing history or something?
Or am I going nuts?

Thanks,
Tiny, oops, Tony