Your are correct. Canada back in 1990 or so switched to it's own, metric, specification instead of just going by the DOT regs, and while they were at it, made the 10% "+" overfill the norm, so a DOT/TC-rated LP tank like this one that has a US fill pressure of 2640 psi with the plus and 2400 psi without in Canada has a single fill pressure of 184 bar - which works out to about 2668 psi. Metric spec tanks can be spotted by the M between the TC material designator - 3ALM or 3AAM - and the fill pressure in bar.
The DOT was going to do something similar at one point, to get rid of the "+" but ended up adding the new UN tank specification instead.
Older, pre-metric tanks can still be rated for the "+" in Canada.