It was probably nostalgia because it likely reminded you of one of the few good things from your childhood. From your post, you sound like those things were few and far between, but for most people feelings of nostalgia come more often and remind them of a better time (usually when they were kids/had no responsibilities) - for most people these can be anything from going back to their old high school a decade after graduation, some pop song by Britney Spears or even hearing of an actor that was around their age (for me Hilary Duff is that actress despite her being a few years older than me).
To extrapolate on the Hilary Duff example, for me it goes like this:
>hear something about her
>think of her old show "Lizzie McGuire" (I wasn't even a fan of it)
>that show makes me think of The Family Channel (which I watched a fuckload of)
>show was early 2000s so I would have been in elementary school when it was on
>at that age I wasn't depressed, had a bright future, was ignorant to the ills of the world, and my biggest priorities were getting better at hockey and seeing my friends at school
Smells are another big thing too. For me a big one is actually gross: it's the smell of a small town hockey arena that's had lots of games played that way; it smells of sweat, and greasy food - the latter being from the canteen. The humid air and the stench of sweat is something that I have a fond association with due to having played hockey for about a decade as a kid; I was always happy there. The greasy smell of the food makes me think of getting a hot dog and/or fries after a game, or having it at lunch on a weekend when we had an all day tournament and my team had to play two or three games that day.
If you really go deeper, you'll notice that people -and entire generations- do this en masse. Just look at fashion or music or movies/TV for example. People who grew up in the 80s will still sometimes reminisce about that time, but not in an overt -or even necessarily conscience- way. They'll fondly remember horrible songs and marathon stupid TV shows thinking it's due to it being or quality; it's really more about how it makes them feel, or rather how they felt when they were first exposed to it. Not to imply that it's a weird sort of Stockholm Syndrome but rather that we connect it in a way as to say that it was responsible in some way to how we felt.
Hell, my generation of channers seems to (as do I) have nostalgia for chans that aren't even that far removed; as in 4chan pre-2010ish. We remember a time when memes didn't feel forced and weren't posted on Facebook, when celebrities never tweeted them thinking they were just cute pics that someone made on tumblr, when 4chan was like a secret club rather than what it's become, when there was actually a feeling of a real like minded community rather than normal people coming from social media sites to "see what the place is all about" just to bring their own culture in to disrupt it, etc. 8chan at first had a bit of a feeling of that period in time, but it's mostly faded as the internet has changed so vastly. What's funny to me is that all the people who are like 15 who will just be finding sites like ours will post similar things in a few years talking about "better times" when people still used Twitter, and when chans didn't have voting systems, etc.
Sorry if this was all rambling and/or didn't help; I tend to get lost in my thoughts.