I don't know enough about guavas, but on other plants, that sort of damage means a bad case of aphids when the leaf was new. Hope this helps!

Kevin : )

It means that your cute Guava is still recovering...
It will get fully recovered in few months, so there is nothing to worry about

And when there is one or two bad leaves among so many good ones, there is nothing to bother about!! :)

As a rule when tropical plants get hit by unusually cold temps it affects their ability to take up water, so they suffer the same effects as drought. Provided it receives no further setbacks it should make a full recovery. Just to be sure, check the underside of the leaves for pests, however.