What's going on with this tingly/chill relaxing feeling that happens only at certain moments?

I get this quite a bit too, it's most definitely always ociated with good, positive feelings about something. Whether it's like you say, a new understanding or listening to an amazing bit of music.. I get goosebumps when the weather is baking, and it's like a little "high" feeling. It goes within about 20-30 seconds i'd say. It's good!