a few things:
1. up'd items are the only ones where socket CAN increase the lvl req. the formula is simple, lvl req = lvl req of socket + 5 (if that results exceeds base lvl req).
so if you up an item and the new level req is still 30 or under, but you try and add a shael rune (lvl 29 req) the new lvl req becomes 29 + 5 = 34. but if an up'd item has lvl 30, and you add a lvl 25 jewel, it stays 30 (25 + 5 = 30)
2. this item is has not been up'd, so the formula = simpler. if you socket with something that requires 30 or under new lvl req = 30. if you put in ist, new lvl req = ist lvl req. etc. it will stay 30 unless u add something.
3. whether an item has been up'd or not, if u hel rune remove the socket lvl req goes back down
Oh thats dope, I didnt know it could revert back down. Thanks for clearing thesnipa, you were always big pro back in the day