Yes, for 11-meters, there's supposed to be a frequency offset on SSB vs AM. However, it seems a lot of people (and some techs) don't know this (because they've never read the alignment procedures for their radio).
SO, when they look at their frequency counters on SSB, they "think" they're transmitting "off" frequency on SSB, and then turn a couple of pots so that they're transmitting on the same frequency as AM. This is NOT how it's supposed to be.
There's a frequency offset on LSB and USB from AM for a reason, but the golden screwdrivers out there don't seem to get it.
You might as well conform with the misinformed. Since 95% of CB operators out there transmit (on SSB) on the same frequency as AM, you might as well do the same. Otherwise you'll hear a lot of reports of you being "WAY" off-frequency (even though you're technically not).
What can I say? Your radio is technically both wrong and right as the same time.