PSA levels increase. When to be concerned?

Hello. My 52 year old husband had his PSA level checked last September and it was 1.1. In April of this year, a cardiologist added a PSA level to a group of other lab work and it came back as 3.3 but nobody addressed the increase (not his specialty I guess). Last week at a free screening a urologist noted the increase from April and said above 3 is high for his age. Plus the fact of the degree of increase, it warranted another check. The repeat last week is now 2.35.
We are still waiting to hear back from the urologist but was wondering if just the fact that it was 2x what it was last year, is this cause for concern? Or does this sound ok?