The wiki says, "Attribute bonuses not used at one level (or surplus points past 10 in the skills governed by an attribute) do not roll over to the next level."

However, I do recall once that I had gained a few levels, cashed them in all at once, and was able to get more than +1 on levels after the first. How could this be if the bonuses don't roll over?

When you have raised Majors ten times, and are eligible for leveling, the skill-ups contributing to the bonuses for that level are "frozen," whether or not you level immediately. The next level's tally then begins, keeping track of skill-ups since the last "freeze," and so on. You could put off leveling for a long time, and then advance several levels in rapid succession, but for each level, you only are awarded the bonuses earned for that level.

It was a long time now since I did any leveling so I didn′t want to post, but glargg is right sure enough

gotcha...thanks for the clarification.

To my experience, that is true to an extend. After a character is eligible to level up, any skill ups after that do go toward the next level. However, if a character is eligible to level up a second time (hence eligible for 2 level ups in a row), the skill ups gained for the second level up are frozen and any subsequent skill ups for the 3rd level are completely ignored/ do not contribute to anymore attribute bonuses until the first two level ups are used. So, AFAIK, it can be done for two level ups in a row, but not more than that.