Should I be able to hear a 4Hz difference in my speakers?

neither speaker is putting out 28 hz or 32 hz at full volume to the listening position, so many other factors at play...properly set up and with good room acoustics the Forest bass will sound better and deeper...

You must realize that the specification is measured for a specific response (power level).
At 28-32 Hz the amplitude will be at any where from -3 db to -16 db or more.
Only if the range (25-35 Hz) is audible.
And yes you should be able to discern this difference.

Good question!

28-32hz - you might be able to feel rather than hear the bass in that range a bit more if a) its in the recording b) the rest of your system has good response down to below 28hz and c) the room acoustics support it, but probably a very marginal difference that may be hard to determine at best.

Many instruments can produce sound in that range, including synthesizer, tuba, bassoon, harp, organ, and piano.

So even if in the recording to start with, speaker response low enough to reproduce it alone does not mean you will hear it.

You can always run test tones through your system and see what happens.

Totem’s specs say "in room" meaning that 28hz (listed as 30hz on another "spec sheet" near the manual download page) rating requires reinforcement from room boundaries. Every speaker I’ve owned over the last several years have been positioned away from walls to lesson the room boom effect to some degree, and I suggest using a test CD (I have a few of the Stereophile test CDs and they’re great) to see actually how low these things go. My guess is even though Totems are cool well made speakers (Forest Signatures seem very nice), they’re never going to produce much at 28hz without a room doing some of the heavy lifting...that’s sub territory.

How old are/were the Hawks vs the Forests?  

My Forests (not Signatures) took a long time for bass to come in.  If the Forests are new vs the Hawks being well-used, I can readily believe it's hard to hear a difference in their bass output (yet).