How does a temporary Knowledge bonus effect existing knowledge rolls?

Question

Lets say I encounter a marauding Owlbear. As it is a magical beast and I know a few things about the arcane I make a knowledge arcana check. I get a final result of 23 giving me two pieces of useful information (as I beat the DC 14 check by 9). Now sometime later that fight I cast Heightened Awareness on myself (maybe the owlbear hid and I really want that +2 to perception)

You enter a heightened state of awareness that allows you to notice more about your surroundings and recall information effortlessly. You gain a +2 competence bonus on Perception checks and on all Knowledge checks that you are trained in.

How does the +2 knowledge bonus interact with my knowledge of the Owlbear. The SRD states (In reference to knowledge checks):

Retry? No. The check represents what you know, and thinking about a topic a second time doesn’t let you know something that you never learned in the first place.

Do I reroll it since my bonus changed? Do I add my bonus to my old roll? Do I gain no new knowledge? Does some other thing occur?

Answer 1

The effect of the spell includes a bonus on Knowledge checks. That means that, for checks made during the duration of the spell, you have that bonus.

But the check you’re talking about was rolled outside the duration of the spell (specifically, prior to it). The bonus has no effect on it. It only affects checks made during that duration.

And the Knowledge rules state that you cannot make a new check about owlbears now that you have the bonus, and nothing about the spell counter-acts that situation.

Ultimately, though, I’d personally consider the failure of the Knowledge rules to have any consideration for the possibility of the Knowledge bonus changing to be a (fairly minor, to be fair) lack in the rules. I would probably want to houserule something in, as a DM, to account for that. But you’ll have to ask your DM if he feels that anything should deviate from the rules, and if so, how.